In situ solidifying homogeneous solutions and methods of making and using thereof

ABSTRACT

Described herein are fluid complex coacervates that produce solid adhesives in situ. Oppositely charged polyelectrolytes were designed to form fluid adhesive complex coacervates at ionic strengths higher than the ionic strength of the application site, but an insoluble adhesive solid or gel at the application site. When the fluid, high ionic strength adhesive complex coacervates are introduced into the lower ionic strength application site, the fluid complex coacervate is converted to a an adhesive solid or gel as the salt concentration in the complex coacervate equilibrates to the application site salt concentration. In one embodiment, the fluid complex coacervates are designed to solidify in situ at physiological ionic strength and have numerous medical applications. In other aspects, the fluid complex coacervates can be used in aqueous environment for non-medical applications.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 15/880,650, filed on Jan. 26, 2018, which is a is a continuationapplication of U.S. application Ser. No. 15/325,885, filed on Jan. 12,2017, which is a U.S. national phase application under 35 USC 371 ofinternational application number PCT/US2015/040377, filed Jul. 14, 2015,which claims priority to U.S. provisional application Ser. No.62/024,128, filed Jul. 14, 2014. These applications are herebyincorporated by reference in their entireties for all of theirteachings.

ACKNOWLEDGEMENTS

This invention was made with government support under R01 HD075863awarded by the National Institutes of Health and N00014-13-1-0577awarded by the Office of Naval Research. The government has certainrights in the invention.

CROSS REFERENCE TO SEQUENCE LISTING

Proteins described herein are referred to by a sequence identifiernumber (SEQ ID NO). The SEQ ID NO corresponds numerically to thesequence identifiers <400>1, <400>2, etc. The Sequence Listing, inwritten computer readable format (CFR), is incorporated by reference inits entirety.

BACKGROUND

Numerous in situ gelling systems have been developed based on severalgelling mechanisms. Reactive monomers or macromers can be chemicallypolymerized into hydrogels after placement in tissue. An example of thisis the photoinitiated in situ polymerization ofpolyethyleneglycol-diacrylate (PEG-dA) macromers. Polymers withchemically reactive moieties can be chemically crosslinked in situ uponmixing with a second reactive component during or just prior toplacement. An example of this approach is multi-armed PEG macromersterminated with activated ester groups. When mixed with multi-valentamines or thiols the components covalently crosslink into hydrogels.Thermosetting in situ hydrogels exploit temperature dependenttransitions from viscous injectable polymer solutions to solidhydrogels. An example is ABA-type block copolymers of PEG andpolypropylene oxide (PPO), which have a lower critical solutiontemperature (LCST) below mammalian physiological temperature. Thesolutions are injectable below the LCST but solidify in situ as thetemperature equilibrates to the physiological temperature above theLCST. Additional in situ gelling systems depend on specific interactionsbetween receptors and ligands, such as antibodies and antigens, onseparated polymers.

Potential clinical applications of in situ gelling systems include drugdelivery depots to control the release kinetics of therapeuticsentrapped within the gel. Other uses include tissue augmentation forcosmetic purposes and to fill tissue voids resulting from accidentaltrauma or surgical resection. Systems that gel or solidify in situ arealso used to block the flow of blood in blood vessels by controlledcreation of localized emboli.

Current embolic agents have serious drawbacks. Cyanoacrylate (CA)adhesives are used in some cases as embolization agents. Thecyanoacrylate monomers rapidly polymerize into a hard resin when theycontact water in the blood vessel. CA is difficult to control,polymerizes rapidly, and can glue the end of the catheter to the bloodvessels making catheter removal difficult. Onyx® is an injectabledimethylsulfoxide (DMSO) solution of ethylenevinyl alcohol. When it isinjected into a watery physiological environment, the DMSO solventdiffuses out of the material causing the ethylenevinyl alcohol, which isinsoluble in water, to precipitate. A drawback of Onyx® is that it canbe used only in small amounts because of the toxicity of the DMSOsolvent.

SUMMARY

Described herein are fluid complex coacervates that produce solidadhesives in situ. Oppositely charged polyelectrolytes were designed toform fluid adhesive complex coacervates at ionic strengths higher thanthe ionic strength of the application site, but an insoluble adhesivesolid or gel at the application site. When the fluid, high ionicstrength adhesive complex coacervates are introduced into the lowerionic strength application site, the fluid adhesive complex coacervateis converted to an adhesive solid or gel as the salt concentration inthe complex coacervate equilibrates to the application site saltconcentration. In one embodiment, the fluid complex coacervates aredesigned to solidify in situ at physiological ionic strength and havenumerous medical applications. In other aspects, the fluid complexcoacervates can be used in aqueous environment for non-medicalapplications.

The advantages of the invention will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the aspects describedbelow. The advantages described below will be realized and attained bymeans of the elements and combinations particularly pointed out in theappended claims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several aspects described below.

FIG. 1 shows aqueous solutions of protamine and hexametaphosphate mixedin various concentrations of NaCl. Between 1100 and 1200 mM NaCl acritical ionic strength (I) exists at which the complex coacervatebecomes a solid non-flowing gel. The viscosity of the coacervatedecreases with increasing I above I_(crit). The stiffness of the gelsincreases below I_(crit). The forms are interconvertible by changing theionic strength.

FIG. 2 shows viscosity versus ionic strength of a syntheticpolyphosphate and protamine mixed at a 1:1 macroion charge ratio.

FIG. 3 shows an in vitro vascular model with a bifurcated flow path. Anarrow catheter was inserted into one side of the flow path for in flowinjection of an adhesive complex coacervate. By closing the oppositeside, the pressure maintained by the embolism can be determined.

FIGS. 4A-4C show the use of an in situ solidifying complex coacervate asembolic agent in an in vitro model composed a bifurcated vascular systemcreated with silicone tubing and a peristaltic pump.

FIG. 5 shows the synthesis of N-(3-methacrylamidopropyl) guanidiniumchloride.

FIG. 6A shows the structure of co-polyguinidium copolymerized with asmall amount of fluorescein methacrylate for visualization. FIG. 6Bshows the structure of co-polyguinidium with methacrylamide sidechainsfor crosslinking.

FIGS. 7A and 7B show fluoroscopic images of embolized kidney. FIGS. 7Cand 7D show the three dimensional CT images of embolized kidney postmortem.

FIG. 8A shows low magnification of cross-sectioned occluded arteriolesin the cortex of an embolized kidney. FIG. 8B shows higher magnificationof glomerulus with occluded arterioles and capillaries of an embolizedkidney. FIG. 8C shows low magnification of longitudinal-sectionedoccluded arterioles in the cortex of an embolized kidney. FIG. 8D showshigher magnification of occluded arteries of an embolized kidney.

FIG. 9 shows the flow behavior of PRT/IP6 complex coacervates with andwithout 30 wt % tantalum contrast agent.

FIG. 10A shows the phase diagram of PRT/IP6 polyelectrolyte mixturesover a range of NaCl concentrations at 37° C. FIG. 10B shows the phasediagram of PRT/IP6 polyelectrolyte mixtures over a range of NaClconcentrations at 21° C.

DETAILED DESCRIPTION

Before the present compounds, compositions, articles, devices, and/ormethods are disclosed and described, it is to be understood that theaspects described below are not limited to specific compounds, syntheticmethods, or uses as such may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular aspects only and is not intended to be limiting.

In this specification and in the claims that follow, reference will bemade to a number of terms that shall be defined to have the followingmeanings:

It must be noted that, as used in the specification and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “a pharmaceutical carrier” includes mixtures of two or moresuch carriers, and the like.

“Optional” or “optionally” means that the subsequently described eventor circumstance can or cannot occur, and that the description includesinstances where the event or circumstance occurs and instances where itdoes not. For example, the phrase “optionally substituted lower alkyl”means that the lower alkyl group can or cannot be substituted and thatthe description includes both unsubstituted lower alkyl and lower alkylwhere there is substitution.

Ranges may be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect includes from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint.

References in the specification and concluding claims to parts byweight, of a particular element or component in a composition orarticle, denotes the weight relationship between the element orcomponent and any other elements or components in the composition orarticle for which a part by weight is expressed. Thus, in a compoundcontaining 2 parts by weight of component X and 5 parts by weightcomponent Y, X and Y are present at a weight ratio of 2:5, and arepresent in such ratio regardless of whether additional components arecontained in the compound.

A weight percent of a component, unless specifically stated to thecontrary, is based on the total weight of the formulation or compositionin which the component is included.

The term “alkyl group” as used herein is a branched or unbranchedsaturated hydrocarbon group of 1 to 25 carbon atoms, such as methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl,heptyl, octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyl and thelike. Examples of longer chain alkyl groups include, but are not limitedto, a palmitate group. A “lower alkyl” group is an alkyl groupcontaining from one to six carbon atoms.

The term “cycloalkyl group” as used herein is a non-aromaticcarbon-based ring composed of at least three carbon atoms. Examples ofcycloalkyl groups include, but are not limited to, cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, etc. The term “heterocycloalkylgroup” is a cycloalkyl group as defined above where at least one of thecarbon atoms of the ring is substituted with a heteroatom such as, butnot limited to, nitrogen, oxygen, sulphur, or phosphorus.

The term “aryl group” as used herein is any carbon-based aromatic groupincluding, but not limited to, benzene, naphthalene, etc. The term “arylgroup” also includes “heteroaryl group,” which is defined as an aromaticgroup that has at least one heteroatom incorporated within the ring ofthe aromatic group. Examples of heteroatoms include, but are not limitedto, nitrogen, oxygen, sulfur, and phosphorus. In one aspect, theheteroaryl group is imidazole. The aryl group can be substituted orunsubstituted. The aryl group can be substituted with one or more groupsincluding, but not limited to, alkyl, alkynyl, alkenyl, aryl, halide,nitro, amino, ester, ketone, aldehyde, hydroxy, carboxylic acid, oralkoxy.

The term “nucleophilic group” includes any groups capable of reactingwith an activated ester. Examples include amino groups, thiols groups,hydroxyl groups, and their corresponding anions.

The term “carboxyl group” includes a carboxylic acid and thecorresponding salt thereof.

The term “amino group” as used herein is represented as the formula—NHRR′, where R and R′ can be any organic group including alkyl, aryl,carbonyl, heterocycloalkyl, and the like, where R and R′ can be separategroups or be part of a ring. For example, pyridine is a heteroaryl groupwhere R and R′ are part of the aromatic ring.

The term “treat” as used herein is defined as maintaining or reducingthe symptoms of a pre-existing condition. The term “prevent” as usedherein is defined as eliminating or reducing the likelihood of theoccurrence of one or more symptoms of a disease or disorder. The term“reduce” as used herein is the ability of the in situ solidifyingcomplex coacervate described herein to completely eliminate the activityor reduce the activity when compared to the same activity in the absenceof the complex coacervate.

“Subject” refers to mammals including, but not limited to, humans,non-human primates, sheep, dogs, rodents (e.g., mouse, rat, etc.),guinea pigs, cats, rabbits, cows, and non-mammals including chickens,amphibians, and reptiles.

“Physiological conditions” refers to condition such as pH, temperature,etc. within the subject. For example, the physiological pH andtemperature of a human is 7.2 and 37° C., respectively.

In Situ Solidifying Complex Coacervates

Polyelectrolytes with opposite net charges in aqueous solution canassociate into several higher order morphologies depending on thesolution conditions and charge ratios. They can form stable colloidalsuspensions of polyelectrolyte complexes with net surface charges.Repulsion between like surface charges stabilize the suspension fromfurther association. When the polyelectrolyte charge ratios arebalanced, or near balance, the initial complexes can further coalesceand settle out into a dense fluid phase in which the opposite macroioncharges are approximately equal. This process is referred to as complexcoacervation, and the dense fluid morphology as a complex coacervate.More descriptively, the process is an associative macrophase separationof an aqueous solution of two oppositely charged polyelectrolytes intotwo liquid phases, a dense concentrated polyelectrolyte phase inequilibrium with a polyelectrolyte depleted phase. The aqueouscoacervate phase can be dispersed into the aqueous depleted phase butquickly settles back out, like oil droplets in water. The spontaneousdemixing of paired polyelectrolytes into complex coacervates occurs whenattractive forces between polyelectrolyte pairs are stronger thanrepulsive forces. In thermodynamic terms, the net negative change infree energy that drives complex coacervation derives primarily from thegain in entropy of the small counterions released when macroionsassociate, which overcomes the loss of configurational entropy of thefully solvated polyelectrolytes.

A non-limiting example of the different morphologies that can beproduced from polyelectrolytes with opposite net charges is provided inFIGS. 1 and 10. As shown in the phase diagrams in FIGS. 10A and 10B,varying parameters such as charge ratio of the polyelectrolytes,temperature, salt concentration, and pH can result in the formation of agel, a complex coacervate, or a clear homogeneous solution, i.e., nophase separation (FIG. 1). By mixing polyelectrolytes in a region of thephase diagram in which fluid complex coacervates form, the in situsolidifying complex coacervates described herein can be prepared in afluid form. If the fluid form is introduced into an environmentcorresponding to a gel region of the phase diagram (FIG. 10), the fluidform will harden into a solid gel as the in situ solidifying complexcoacervate equilibrates to the new solution conditions. The term “gel”is defined herein as non-fluid colloidal network or polymer network thatis expanded throughout its whole volume by a fluid. IUPAC. Compendium ofChemical Terminology, 2nd ed. (the “Gold Book”). Compiled by A. D.McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford(1997). Conversely, the fluid complex coacervates described herein areliquids. Thus, the fluid complex coacervates described herein have acompletely different morphology compared to corresponding gels producedin situ despite the fact that the polycation and polyanion in the fluidcomplex coacervate and the gel are identical.

The components used to produce the in situ solidifying complexcoacervates described herein as well as their applications thereof areprovided below.

I. Polycations

The polycation is generally composed of a polymer backbone with aplurality of cationic groups at a particular pH. The cationic groups canbe pendant to the polymer backbone and/or incorporated within thepolymer backbone. In certain aspects, (e.g., biomedical applications),the polycation is any biocompatible polymer possessing cationic groupsor groups that can be readily converted to cationic groups by adjustingthe pH. In one aspect, the polycation is a polyamine compound. The aminogroups of the polyamine can be branched or part of the polymer backbone.The amino group can be a primary, secondary, or tertiary amino groupthat can be protonated to produce a cationic ammonium group at aselected pH. In general, the polyamine is a polymer with a large excessof positive charges relative to negative charges at the relevant pH, asreflected in its isoelectric point (pI), which is the pH at which thepolymer has a net neutral charge. The number of amino groups present onthe polycation ultimately determines the charge density of thepolycation at a particular pH. For example, the polycation can have from10 to 90 mole %, 10 to 80 mole %, 10 to 70 mole %, 10 to 60 mole %, 10to 50 mole %, 10 to 40 mole %, 10 to 30 mole %, or 10 to 20 mole % aminogroups. In one aspect, the polyamine has excess positive charges at a pHof about 7, with a pI significantly greater than 7. As will be discussedbelow, additional amino groups can be incorporated into the polymer inorder to increase the pI value.

In one aspect, the amino group can be derived from a residue of lysine,histidine, or arginine attached to the polycation. For example, argininehas a guanidinyl group, where the guanidinyl group is a suitable aminogroup useful herein. Any anionic counterions can be used in associationwith the cationic polymers. The counterions should be physically andchemically compatible with the essential components of the compositionand do not otherwise unduly impair product performance, stability oraesthetics. Non-limiting examples of such counterions include halides(e.g., chloride, fluoride, bromide, iodide), sulfate, methylsulfate,acetate and other monovalent carboxylic acids.

In one aspect, the polycation can be a positively-charged proteinproduced from a natural organism. For example, a recombinant P.californica protein can be used as the polycation. In one aspect, Pc1,Pc2, Pc4-Pc18 (SEQ ID NOS 1-17) can be used as the polycation. The typeand number of amino acids present in the protein can vary in order toachieve the desired solution properties. For example, Pc1 is enrichedwith lysine (13.5 mole %) while Pc4 and Pc5 are enriched with histidine(12.6 and 11.3 mole %, respectively).

In another aspect, the polycation is a recombinant protein produced byartificial expression of a gene or a modified gene or a composite genecontaining parts from several genes in a heterologous host such as, forexample, bacteria, yeast, cows, goats, tobacco, and the like.

In another aspect, the polycation can be a biodegradable polyamine. Thebiodegradable polyamine can be a synthetic polymer ornaturally-occurring polymer. The mechanism by which the polyamine candegrade will vary depending upon the polyamine that is used. In the caseof natural polymers, they are biodegradable because there are enzymesthat can hydrolyze the polymer chain. For example, proteases canhydrolyze natural proteins like gelatin. In the case of syntheticbiodegradable polyamines, they also possess chemically labile bonds. Forexample, β-aminoesters have hydrolyzable ester groups. In addition tothe nature of the polyamine, other considerations such as the molecularweight of the polyamine and crosslink density of the adhesive can bevaried in order to modify the rate of biodegradability.

In one aspect, the biodegradable polyamine includes a polysaccharide, aprotein, or a synthetic polyamine. Polysaccharides bearing one or moreamino groups can be used herein. In one aspect, the polysaccharide is anatural polysaccharide such as chitosan or chemically modified chitosan.Similarly, the protein can be a synthetic or naturally-occurringcompound. In another aspect, the biodegradable polyamine is a syntheticpolyamine such as poly(β-aminoesters), polyester amines, poly(disulfideamines), mixed poly(ester and amide amines), and peptide crosslinkedpolyamines.

In the case when the polycation is a synthetic polymer, a variety ofdifferent polymers can be used; however, in certain applications suchas, for example, biomedical applications, it is desirable that thepolymer be biocompatible and non-toxic to cells and tissue. In oneaspect, the biodegradable polyamine can be an amine-modified naturalpolymer. For example, the amine-modified natural polymer can be gelatinmodified with one or more alkylamino groups, heteroaryl groups, or anaromatic group substituted with one or more amino groups. Examples ofalkylamino groups are depicted in Formulae IV-VI

wherein R¹³-R²² are, independently, hydrogen, an alkyl group, or anitrogen containing substituent;s, t, u, v, w, and x are an integer from 1 to 10; andA is an integer from 1 to 50,where the alkylamino group is covalently attached to the naturalpolymer. In one aspect, if the natural polymer has a carboxyl group(e.g., acid or ester), the carboxyl group can be reacted with analkyldiamino compound to produce an amide bond and incorporate thealkylamino group into the polymer. Thus, referring to formulae IV-VI,the amino group NR¹³ is covalently attached to the carbonyl group of thenatural polymer.

As shown in formula IV-VI, the number of amino groups can vary. In oneaspect, the alkylamino group is —NHCH₂NH₂, —NHCH₂CH₂NH₂,—NHCH₂CH₂CH₂NH₂, —NHCH₂CH₂CH₂CH₂NH₂, —NHCH₂CH₂CH₂CH₂CH₂NH₂,—NHCH₂NHCH₂CH₂CH₂NH₂, —NHCH₂CH₂NHCH₂CH₂CH₂NH₂,—NHCH₂CH₂CH₂NHCH₂CH₂CH₂CH₂NHCH₂CH₂CH₂NH₂, —NHCH₂CH₂NHCH₂CH₂CH₂CH₂NH₂,—NHCH₂CH₂NHCH₂CH₂CH₂NHCH₂CH₂CH₂NH₂, or—NHCH₂CH₂NH(CH₂CH₂NH)_(d)CH₂CH₂NH₂, where d is from 0 to 50.

In one aspect, the amine-modified natural polymer can include an arylgroup having one or more amino groups directly or indirectly attached tothe aromatic group. Alternatively, the amino group can be incorporatedin the aromatic ring. For example, the aromatic amino group is apyrrole, an isopyrrole, a pyrazole, imidazole, a triazole, or an indole.In another aspect, the aromatic amino group includes the isoimidazolegroup present in histidine. In another aspect, the biodegradablepolyamine can be gelatin modified with ethylenediamine.

In another aspect, the polycation can be a polycationic micelle or mixedmicelle formed with cationic surfactants. The cationic surfactant can bemixed with nonionic surfactants to create micelles with variable chargedensities. The micelles are polycationic by virtue of the hydrophobicinteractions that form a polyvalent micelle. In one aspect, the micelleshave a plurality of amino groups capable of reacting with the activatedester groups present on the polyanion.

Examples of nonionic surfactants include the condensation products of ahigher aliphatic alcohol, such as a fatty alcohol, containing about 8 toabout 20 carbon atoms, in a straight or branched chain configuration,condensed with about 3 to about 100 moles, preferably about 5 to about40 moles, most preferably about 5 to about 20 moles of ethylene oxide.Examples of such nonionic ethoxylated fatty alcohol surfactants are theTergitol™ 15-S series from Union Carbide and Brij™ surfactants from ICI.Tergitol™ 15-S Surfactants include C₁₁-C₁₅ secondary alcoholpolyethyleneglycol ethers. Brij™97 surfactant is polyoxyethylene(10)oleyl ether; Brij™58 surfactant is polyoxyethylene(20) cetyl ether; andBrij™ 76 surfactant is polyoxyethylene(10) stearyl ether.

Another useful class of nonionic surfactants include the polyethyleneoxide condensates of one mole of alkyl phenol containing from about 6 to12 carbon atoms in a straight or branched chain configuration, withethylene oxide. Examples of nonreactive nonionic surfactants are theIgepal™ CO and CA series from Rhone-Poulenc. Igepal™ CO surfactantsinclude nonylphenoxy poly(ethyleneoxy)ethanols. Igepal™ CA surfactantsinclude octylphenoxy poly(ethyleneoxy)ethanols.

Another useful class of hydrocarbon nonionic surfactants include blockcopolymers of ethylene oxide and propylene oxide or butylene oxide.Examples of such nonionic block copolymer surfactants are the Pluronic™and Tetronic™ series of surfactants from BASF. Pluronic™ surfactantsinclude ethylene oxide-propylene oxide block copolymers. Tetronic™surfactants include ethylene oxide-propylene oxide block copolymers.

In other aspects, the nonionic surfactants include sorbitan fatty acidesters, polyoxyethylene sorbitan fatty acid esters and polyoxyethylenestearates. Examples of such fatty acid ester nonionic surfactants arethe Span™, Tween™, and Myj™ surfactants from ICI. Span™ surfactantsinclude C₁₂-C₁₈ sorbitan monoesters. Tween™ surfactants includepoly(ethylene oxide) C₁₂-C₁₈ sorbitan monoesters. Myj™ surfactantsinclude poly(ethylene oxide) stearates.

In one aspect, the nonionic surfactant can include polyoxyethylene alkylethers, polyoxyethylene alkyl-phenyl ethers, polyoxyethylene acylesters, sorbitan fatty acid esters, polyoxyethylene alkylamines,polyoxyethylene alkylamides, polyoxyethylene lauryl ether,polyoxyethylene cetyl ether, polyoxyethylene stearyl ether,polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether,polyoxyethylene nonylphenyl ether, polyethylene glycol laurate,polyethylene glycol stearate, polyethylene glycol distearate,polyethylene glycol oleate, oxyethylene-oxypropylene block copolymer,sorbitan laurate, sorbitan stearate, sorbitan distearate, sorbitanoleate, sorbitan sesquioleate, sorbitan trioleate, polyoxyethylenesorbitan laurate, polyoxyethylene sorbitan stearate, polyoxyethylenesorbitan oleate, polyoxyethylene laurylamine, polyoxyethylenelaurylamide, laurylamine acetate, hard beef tallow propylenediaminedioleate, ethoxylated tetramethyldecynediol, fluoroaliphatic polymericester, polyether-polysiloxane copolymer, and the like.

Examples of cationic surfactants useful for making cationic micellesinclude alkylamine salts and quaternary ammonium salts. Non-limitingexamples of cationic surfactants include: the quaternary ammoniumsurfactants, which can have up to 26 carbon atoms include: alkoxylatequaternary ammonium (AQA) surfactants as discussed in U.S. Pat. No.6,136,769; dimethyl hydroxyethyl quaternary ammonium as discussed inU.S. Pat. No. 6,004,922; dimethyl hydroxyethyl lauryl ammonium chloride;polyamine cationic surfactants as discussed in WO 98/35002, WO 98/35003,WO 98/35004, WO 98/35005, and WO 98/35006; cationic ester surfactants asdiscussed in U.S. Pat. Nos. 4,228,042, 4,239,660 4,260,529 and U.S. Pat.No. 6,022,844; and amino surfactants as discussed in U.S. Pat. No.6,221,825 and WO 00/47708, specifically amido propyldimethyl amine(APA).

In one aspect, the polycation includes a polyacrylate having one or morependant amino groups. For example, the backbone of the polycation can bederived from the polymerization of acrylate monomers including, but notlimited to, acrylates, methacrylates, acrylamides, and the like. In oneaspect, the polycation backbone is derived from polyacrylamide. In otheraspects, the polycation is a block co-polymer, where segments orportions of the co-polymer possess cationic groups or neutral groupsdepending upon the selection of the monomers used to produce theco-polymer.

In other aspects, the polycation can be a dendrimer. The dendrimer canbe a branched polymer, a multi-armed polymer, a star polymer, and thelike. In one aspect, the dendrimer is a polyalkylimine dendrimer, amixed amino/ether dendrimer, a mixed amino/amide dendrimer, or an aminoacid dendrimer. In another aspect, the dendrimer is poly(amidoamine), orPAMAM. In one aspect, the dendrimer has 3 to 20 arms, wherein each armcomprises an amino group.

In one aspect, the polycation is a polyamino compound. In anotheraspect, the polyamino compound has 10 to 90 mole % primary amino groups.In a further aspect, the polycation polymer has at least one fragment ofthe formula I

wherein R¹, R², and R³ are, independently, hydrogen or an alkyl group, Xis oxygen or NR⁵, where R⁵ is hydrogen or an alkyl group, and m is from1 to 10, or the pharmaceutically-acceptable salt thereof. In anotheraspect, R¹, R², and R³ are methyl and m is 2. Referring to formula I,the polymer backbone is composed of CH₂—CR¹ units with pendant—C(O)X(CH₂)_(m)NR²R³ units. In one aspect, the polycation is the freeradical polymerization product of a cationic primary amine monomer(3-aminopropyl methacrylate) and acrylamide, where the molecular weightis from 10 to 200 kd and possesses primary monomer concentrations from 5to 90 mol %.

In another aspect, the polycation is a protamine. Protamines arepolycationic, arginine-rich proteins that play a role in condensation ofchromatin into the sperm head during spermatogenesis. As by-products ofthe fishing industry, commercially available protamines, purified fromfish sperm, are readily available in large quantity and are relativelyinexpensive. A non-limiting example of a protamine useful herein issalmine. The amino acid sequence of salmine, a protamine isolated fromsalmon sperm, is SEQ ID NO 18. Of the 32 amino acids, 21 are arginine(R). The guanidinyl group on the sidechain of R has a pK_(a) of ˜12.5,making salmine a densely charged polycation at physiologically relevantpH. It has a molecular mass of ˜4,500 g/mol and a single negative chargeat the carboxy terminus. In another aspect, the protamine is clupein.

In one aspect, the protamine can be derivatized with one or morecrosslinkable groups described herein. For example, salmine can bederivatized to include one or more acrylate or methacrylate groups. Anexemplary, non-limiting procedure for this embodiment is provided in theExamples. In this aspect, salmine has been derivatized on the C-terminalcarboxylate with a single methacrylamide group to create a crosslinkablepolycation.

In one aspect, the polycation is a natural polymer wherein one or moreamine present on the natural polymer have been modified with a guanidinegroup. In another aspect, the polycation is a synthetic polymercontaining one or more guanidinyl sidechains. For example, thepolycation can be a synthetic polyguanidinyl polymer having an acrylateor methacrylate backbone and one or more guanidinyl sidechains. Inanother aspect, the polycation polymer has at least one fragment of theformula VIII

wherein R¹ is hydrogen or an alkyl group, X is oxygen or NR⁵, where R⁵is hydrogen or an alkyl group, and m is from 1 to 10, or thepharmaceutically-acceptable salt thereof. In another aspect, R¹, R², andR³ are methyl and m is 2. Referring to formula VIII, the polymerbackbone is composed of CH₂—CR¹ units with pendant—C(O)X(CH₂)_(m)NC(NH)NH₂ units. An example of a synthetic polyguanidinylpolymer useful herein is depicted in FIG. 6. An exemplary, non-limitingprocedure for preparing a synthetic polyguanidinyl polymer is providedin the Examples.

In another aspect, the synthetic polyguanidinyl polymer can bederivatized with one or more crosslinkable groups described herein. Forexample, one or more acrylate or methacrylate groups can be grafted ontothe synthetic polyguanidinyl polymer. FIG. 6B depicts a syntheticpolyguanidinyl polymer with a methacrylate sidechain. An exemplary,non-limiting procedure for this embodiment is provided in the Examples.

II. Polyanions

Similar to the polycation, the polyanion can be a synthetic polymer ornaturally-occurring. Examples of naturally-occurring polyanions includeglycosaminoglycans such as condroitin sulfate, heparin, heparin sulfate,dermatan sulfate, keratin sulfate, and hyaluronic acid. In otheraspects, acidic proteins having a net negative charge at neutral pH orproteins with a low pI can be used as naturally-occurring polyanionsdescribed herein. The anionic groups can be pendant to the polymerbackbone and/or incorporated in the polymer backbone.

When the polyanion is a synthetic polymer, it is generally any polymerpossessing anionic groups or groups that can be readily converted toanionic groups by adjusting the pH. Examples of groups that can beconverted to anionic groups include, but are not limited to,carboxylate, sulfonate, boronate, sulfate, borate, phosphonate, orphosphate. Any cationic counterions can be used in association with theanionic polymers if the considerations discussed above are met.

In one aspect, the polyanion is a polyphosphate. In another aspect, thepolyanion is a polyphosphate compound having from 5 to 90 mole %phosphate groups. For example, the polyphosphate can be anaturally-occurring compound such as, for example, DNA, RNA, or highlyphosphorylated proteins like phosvitin (an egg protein), dentin (anatural tooth phosphoprotein), casein (a phosphorylated milk protein),or bone proteins (e.g. osteopontin).

Alternatively, the polyphosphoserine can be a synthetic polypeptide madeby polymerizing the amino acid serine and then chemicallyphosphorylating the polypeptide. In another aspect, thepolyphosphoserine can be produced by the polymerization ofphosphoserine. In one aspect, the polyphosphate can be produced bychemically or enzymatically phosphorylating a protein (e.g., naturalserine- or threonine-rich proteins). In a further aspect, thepolyphosphate can be produced by chemically phosphorylating apolyalcohol including, but not limited to, polysaccharides such ascellulose or dextran.

In another aspect, the polyphosphate can be a synthetic compound. Forexample, the polyphosphate can be a polymer with pendant phosphategroups attached to the polymer backbone and/or present in the polymerbackbone. (e.g., a phosphodiester backbone).

In another aspect, the polyanion can be a micelle or mixed micelleformed with anionic surfactants. The anionic surfactant can be mixedwith any of the nonionic surfactants described above to create micelleswith variable charge densitites. The micelles are polyanionic by virtueof the hydrophobic interactions that form a polyvalent micelle.

Other useful anionic surfactants include, but are not limited to, alkalimetal and (alkyl)ammonium salts of: 1) alkyl sulfates and sulfonatessuch as sodium dodecyl sulfate, sodium 2-ethylhexyl sulfate, andpotassium dodecanesulfonate; 2) sulfates of polyethoxylated derivativesof straight or branched chain aliphatic alcohols and carboxylic acids;3) alkylbenzene or alkylnaphthalene sulfonates and sulfates such assodium laurylbenzene-4-sulfonate and ethoxylated and polyethoxylatedalkyl and aralkyl alcohol carboxylates; 5) glycinates such as alkylsarcosinates and alkyl glycinates; 6) sulfosuccinates including dialkylsulfosuccinates; 7) isothionate derivatives; 8) N-acyltaurinederivatives such as sodium N methyl-N-oleyltaurate); 9) amine oxidesincluding alkyl and alkylamidoalkyldialkylamine oxides; and 10) alkylphosphate mono or di-esters such as ethoxylated dodecyl alcoholphosphate ester, sodium salt.

Representative commercial examples of suitable anionic sulfonatesurfactants include, for example, sodium lauryl sulfate, available asTEXAPON™ L-100 from Henkel Inc., Wilmington, Del., or as POLYSTEP™ B-3from Stepan Chemical Co, Northfield, Ill.; sodium 25 lauryl ethersulfate, available as POLYSTEP™ B-12 from Stepan Chemical Co.,Northfield, Ill.; ammonium lauryl sulfate, available as STANDAPOL™ Afrom Henkel Inc., Wilmington, Del.; and sodium dodecyl benzenesulfonate, available as SIPONATE™ DS-10 from Rhone-Poulenc, Inc.,Cranberry, N.J., dialkyl sulfosuccinates, having the tradename AEROSOL™OT, commercially available from Cytec Industries, West Paterson, N.J.;sodium methyl taurate (available under the trade designation NIKKOL™CMT30 from Nikko Chemicals Co., Tokyo, Japan); secondary alkanesulfonates such as Hostapur™ SAS which is a Sodium (C₁₄-C₁₇) secondaryalkane sulfonates (alpha-olefin sulfonates) available from ClariantCorp., Charlotte, N.C.; methyl-2-sulfoalkyl esters such as sodiummethyl-2-sulfo(C₁₂₋₁₆)ester and disodium 2-sulfo(C₁₂-C₁₆) fatty acidavailable from Stepan Company under the trade designation ALPHASTE™PC48; alkylsulfoacetates and alkylsulfosuccinates available as sodiumlaurylsulfoacetate (under the trade designation LANTHANOL™ LAL) anddisodiumlaurethsulfosuccinate (STEPANMILD™ SL3), both from StepanCompany; alkylsulfates such as ammoniumlauryl sulfate commerciallyavailable under the trade designation STEPANOL™ AM from Stepan Company,and or dodecylbenzenesulfonic acid sold under BIO-SOFT® AS-100 fromStepan Chemical Co. In one aspect, the surfactant can be a disodiumalpha olefin sulfonate, which contains a mixture of C₁₂ to C₁₆sulfonates. In one aspect, CALSOFT™ AOS-40 manufactured by Pilot Corp.can be used herein as the surfactant. In another aspect, the surfactantis DOWFAX 2A1 or 2G manufactured by Dow Chemical, which are alkyldiphenyl oxide disulfonates.

Representative commercial examples of suitable anionic phosphatesurfactants include a mixture of mono-, di- andtri-(alkyltetraglycolether)-o-phosphoric acid esters generally referredto as trilaureth-4-phosphate commercially available under the tradedesignation HOSTAPHAT™ 340KL from Clariant Corp., as well as PPG-5 cetyl10 phosphate available under the trade designation CRODAPHOS™ SG fromCroda Inc., Parsipanny, N.J.

Representative commercial examples of suitable anionic amine oxidesurfactants those commercially available under the trade designationsAMMONYX™ LO, LMDO, and CO, which are lauryldimethylamine oxide,laurylamidopropyldimethylamine oxide, and cetyl amine oxide, all fromStepan Company.

In one aspect, the polyanion includes a polyacrylate having one or morependant phosphate groups. For example, the polyanion can be derived fromthe polymerization of acrylate monomers including, but not limited to,acrylates, methacrylates, and the like. In other aspects, the polyanionis a block co-polymer, where segments or portions of the co-polymerpossess anionic groups and neutral groups depending upon the selectionof the monomers used to produce the co-polymer.

In one aspect, the polyanion includes two or more carboxylate, sulfate,sulfonate, borate, boronate, phosphonate, or phosphate groups.

In another aspect, the polyanion is a polymer having at least onefragment having the formula XI

wherein R⁴ is hydrogen or an alkyl group;n is from 1 to 10;Y is oxygen, sulfur, or NR³⁰, wherein R³⁰ is hydrogen, an alkyl group,or an aryl group;Z′ is an anionic group or a group that can be converted to an anionicgroup, or the pharmaceutically-acceptable salt thereof.

In one aspect, Z′ in formula XI is carboxylate, sulfate, sulfonate,borate, boronate, a substituted or unsubstituted phosphate, or aphosphonate. In another aspect, Z′ in formula XI is sulfate, sulfonate,borate, boronate, a substituted or unsubstituted phosphate, or aphosphonate, and n in formulae XI is 2.

In another aspect, the polyanion is an inorganic polyphosphatepossessing a plurality of phosphate groups (e.g., (NaPO₃)_(a), where nis 3 to 10). Examples of inorganic phosphates include, but are notlimited to, Graham salts, hexametaphosphate salts, and triphosphatesalts. The counterion of these salts can be monovalent cations such as,for example, Na⁺, K⁺, and NH₄ ⁺.

In another aspect, the polyanion is phosphorylated sugar. The sugar canbe a hexose or pentose sugar. Additionally, the sugar can be partiallyor fully phosphorylated. In one aspect, the phosphorylated sugar isinositol hexaphosphate.

III. Crosslinkable Groups

In certain aspects, the polycations and polyanions can contain groupsthat permit crosslinking between the two polymers upon curing to producenew covalent bonds. The mechanism of crosslinking can vary dependingupon the selection of the crosslinking groups. In one aspect, thecrosslinking groups can be electrophiles and nucleophiles. For example,the polyanion can have one or more electrophilic groups, and thepolycations can have one or more nucleophilic groups capable of reactingwith the electrophilic groups to produce new covalent bonds. Examples ofelectrophilic groups include, but are not limited to, anhydride groups,esters, ketones, lactams (e.g., maleimides and succinimides), lactones,epoxide groups, isocyanate groups, and aldehydes. Examples ofnucleophilic groups are presented below. In one aspect, the polycationand polyanion can crosslink with one another via a Michael addition. Forexample, the polycation can have one or more nucleophilic groups suchas, for example, a hydroxyl or thiol group that can react with anolefinic group present on the polyanion.

In one aspect, the crosslinking group on the polyanion comprises anolefinic group and the crosslinking group on the polycation comprises anucleophilic group that reacts with the olefinic group to produce a newcovalent bond. In another aspect, the crosslinking group on thepolycation comprises an olefinic group and the crosslinking group on thepolyanion comprises a nucleophilic group that reacts with the olefinicgroup to produce a new covalent bond.

In another aspect, the polycation and polyanion each have an actinicallycrosslinkable group. As used herein, “actinically crosslinkable group”in reference to curing or polymerizing means that the crosslinkingbetween the polycation and polyanion is performed by actinicirradiation, such as, for example, UV irradiation, visible lightirradiation, ionizing radiation (e.g. gamma ray or X-ray irradiation),microwave irradiation, and the like. Actinic curing methods arewell-known to a person skilled in the art. The actinically crosslinkablegroup can be an unsaturated organic group such as, for example, anolefinic group. Examples of olefinic groups useful herein include, butare not limited to, an acrylate group, a methacrylate group, anacrylamide group, a methacrylamide group, an allyl group, a vinyl group,a vinylester group, or a styrenyl group. In another aspect, theactinically crosslinkable group can be an azido group. For example,crosslinking can occur between the polycation and polyanion via lightactivated crosslinking through azido groups.

Any of the polymers described above (synthetic or naturally-occurring)that can be used as the polycation and polyanion can be modified toinclude the actinically crosslinkable group.

In another aspect, the crosslinkable group includes adihydroxy-substituted aromatic group capable of undergoing oxidation inthe presence of an oxidant. In one aspect, the dihydroxy-substitutedaromatic group is an ortho-dihydroxy aromatic group capable of beingoxidized to the corresponding quinone. In another aspect, thedihydroxyl-substituted aromatic group is a dihydroxyphenol orhalogenated dihydroxyphenol group such as, for example, DOPA andcatechol (3,4 dihydroxyphenol). For example, in the case of DOPA, it canbe oxidized to dopaquinone. Dopaquinone is capable of either reactingwith a neighboring DOPA group or another nucleophilic group. In thepresence of an oxidant such as oxygen or other additives including, butnot limited to, peroxides, periodates (e.g., NaIO₄), persulfates,permanganates, dichromates, transition metal oxidants (e.g., a Fe⁺³compound, osmium tetroxide), or enzymes (e.g., catechol oxidase), thedihydroxyl-substituted aromatic group can be oxidized.

In one aspect, the polyanion is the polymerization product between twoor more monomers, where one of the monomers has a dihydroxy aromaticgroup covalently attached to the monomer. For example, the polyanion canbe the polymerization product between (1) a phosphate acrylate and/orphosphate methacrylate and (2) a second acrylate and/or secondmethacrylate having a dihydroxy aromatic group covalently bonded to thesecond acrylate or second methacrylate. In another aspect, the polyanionis the polymerization product between methacryloxyethyl phosphate anddopamine methacrylamide. In each of these polymers, an acrylatecontaining the pendant ortho-dihydroxyphenyl residue is polymerized withthe appropriate monomers to produce the polyanion with pendantortho-dihydroxyphenyl residues. Oxidation of ortho-dihydroxyphenylgroups results in orthoquinone groups, a reactive intermediate and cancrosslink (i.e., react) with nucleophiles such as, for example, amino,hydroxyl, or thiol groups via a Michael-type addition to form a newcovalent bond. For example, a lysyl group on the polycation can reactwith the orthoquinone residue on the polyanion to produce new covalentbonds. Other groups such as, for example, tyrosine or alkyl phenolgroups can be used herein. Alkyl phenol groups can be crosslinked withperoxidase enzymes, e.g. horse radish peroxidase in the presence ofH₂O₂. The importance of crosslinking with respect to the use of theadhesive complex coacervates described herein will be discussed below.

In certain aspects, the oxidant used above can be stabilized. Forexample, a compound that forms a complex with periodate that is notredox active can result in a stabilized oxidant. In other words, theperiodate is stabilized in a non-oxidative form and cannot oxidize theortho-dihydroxy-substituted aromatic group while in the complex. Thecomplex is reversible and even if it has a very high stability constantthere is a small amount of uncomplexed periodate formed. Theortho-dihydroxyl-substituted aromatic group competes with the compoundfor the small amount of free periodate. As the free periodate isoxidized more is released from the equilibrium complex. In one aspect,sugars possessing a cis,cis-1,2,3-triol grouping on a six-membered ringcan form competitive periodate complexes. An example of a specificcompound that forms stable periodate complex is1,2-O-isopropylidene-alpha-D-glucofuranose (A. S. Perlin and E. VONRudloff, Canadian Journal of Chemistry. Volume 43 (1965)). Thestabilized oxidant can control the rate of crosslinking. Not wishing tobe bound by theory, the stabilized oxidant slows the rate of oxidationproviding time to add the oxidant and position the substrate before theadhesive hardens irreversibly.

In other aspects, the crosslinkers present on the polycation and/orpolyanion can form coordination complexes with transition metal ions. Inone aspect, the polycation and/or polyanion can include groups capableof coordinating transition metal ions. Examples of coordinatingsidechains are catechols, imidazoles, phosphates, carboxylic acids, andcombinations. The rate of coordination and dissociation can becontrolled by the selection of the coordination group, the transitionmetal ion, and the pH. Thus, in addition to covalent crosslinking asdescribed above, crosslinking can occur through electrostatic, ionic,coordinative, or other non-covalent bonding. Transition metal ions suchas, for example, iron, copper, vanadium, zinc, and nickel can be usedherein. In one aspect, the transition metal is present in an aqueousenvironment at the application site.

In certain aspects, the in situ solidifying complex coacervate can alsoinclude a multivalent crosslinker. In one aspect, the multivalentcrosslinker has two or more nucleophilic groups (e.g., hydroxyl, thiol,etc.) that react with crosslinkable groups (e.g., olefinic groups)present on the polycation and polyanion via a Michael addition reactionto produce a new covalent bond. In one aspect, the multivalentcrosslinker is a di-thiol or tri-thiol compound.

IV. Reinforcing Components

The in situ solidifying complex coacervates described herein canoptionally include a reinforcing component. The term “reinforcingcomponent” is defined herein as any component that enhances or modifiesone or more properties of the fluid complex coacervates described herein(e.g., cohesiveness, fracture toughness, elastic modulus, dimensionalstability after curing, viscosity, etc.) of the in situ solidifyingcomplex coacervate prior to or after the curing of the coacervate whencompared to the same coacervate that does not include the reinforcingcomponent. The mode in which the reinforcing component can enhance themechanical properties of the coacervate can vary, and will depend uponthe intended application of the coacervates as well as the selection ofthe polycation, polyanion, and reinforcing component. For example, uponcuring the coacervate, the polycations and/or polyanions present in thecoacervate can covalently crosslink with the reinforcing component. Inother aspects, the reinforcing component can occupy a space or “phase”in the coacervate, which ultimately increases the mechanical propertiesof the coacervate. Examples of reinforcing components useful herein areprovided below.

In one aspect, the reinforcing component is a polymerizable monomer. Thepolymerizable monomer entrapped in the complex coacervate can be anywater soluble monomer capable of undergoing polymerization in order toproduce an interpenetrating polymer network. In certain aspects, theinterpenetrating network can possess nucleophilic groups (e.g., aminogroups) that can react (i.e., crosslink) with the activated ester groupspresent on the polyanion. The selection of the polymerizable monomer canvary depending upon the application. Factors such as molecular weightcan be altered to modify the solubility properties of the polymerizablemonomer in water as well as the mechanical properties of the resultingcoacervate, The selection of the functional group on the polymerizablemonomer determines the mode of polymerization. For example, thepolymerizable monomer can be a polymerizable olefinic monomer that canundergo polymerization through mechanisms such as, for example, freeradical polymerization and Michael addition reactions. In one aspect,the polymerizable monomer has two or more olefinic groups. In oneaspect, the monomer comprises one or two actinically crosslinkablegroups as defined above.

Examples of water-soluble polymerizable monomers include, but are notlimited to, hydroxyalkyl methacrylate (HEMA), hydroxyalkyl acrylate,N-vinyl pyrrolidone, N-methyl-3-methylidene-pyrrolidone, allyl alcohol,N-vinyl alkylamide, N-vinyl-N-alkylamide, acrylamides, methacrylamide,(lower alkyl)acrylamides and methacrylamides, and hydroxyl-substituted(lower alkyl)acrylamides and -methacrylamides. In one aspect, thepolymerizable monomer is a diacrylate compound or dimethacrylatecompound. In another aspect, the polymerizable monomer is a polyalkyleneoxide glycol diacrylate or dimethacrylate. For example, the polyalkylenecan be a polymer of ethylene glycol, propylene glycol, or blockcopolymers thereof. In one aspect, the polymerizable monomer ispolyethylene glycol diacrylate or polyethylene glycol dimethacrylate. Inone aspect, the polyethylene glycol diacrylate or polyethylene glycoldimethacrylate has a M_(n) of 200 to 2,000, 400 to 1,500, 500 to 1,000,500 to 750, or 500 to 600.

In certain aspects, the interpenetrating polymer network isbiodegradable and biocompatible for medical applications. Thus, thepolymerizable monomer is selected such that a biodegradable andbiocompatible interpenetrating polymer network is produced uponpolymerization. For example, the polymerizable monomer can possesscleavable ester linkages. In one aspect, the polymerizable monomer ishydroxypropyl methacrylate (HPMA), which will produce a biocompatibleinterpenetrating network. In other aspects, biodegradable crosslinkerscan be used to polymerize biocompatible water soluble monomers such as,for example, alkyl methacrylamides. The crosslinker could beenzymatically degradable, like a peptide, or chemically degradable byhaving an ester or disulfide linkage. In another aspect, the reinforcingcomponent can be a natural or synthetic fiber.

In other aspects, the reinforcing component can be a water-insolublefiller. The filler can have a variety of different sizes and shapes,ranging from particles (micro and nano) to fibrous materials. Theselection of the filler can vary depending upon the application of thein situ solidifying complex coacervate.

The fillers useful herein can be composed of organic and/or inorganicmaterials. In one aspect, the nanostructures can be composed of organicmaterials like carbon or inorganic materials including, but not limitedto, boron, molybdenum, tungsten, silicon, titanium, copper, bismuth,tungsten carbide, aluminum oxide, titanium dioxide, molybdenumdisulphide, silicon carbide, titanium diboride, boron nitride,dysprosium oxide, iron (III) oxide-hydroxide, iron oxide, manganeseoxide, titanium dioxide, boron carbide, aluminum nitride, or anycombination thereof.

In certain aspects, the fillers can be functionalized in order to react(i.e., crosslink) with the polycation and/or polyanion. For example, thefiller can be functionalized with amino groups or activated estergroups. In other aspects, it is desirable to use two or more differenttypes of fillers. For example, a carbon nanostructure can be used incombination with one or more inorganic nanostructures.

In one aspect, the filler comprises a metal oxide, a ceramic particle,or a water insoluble inorganic salt. Examples of fillers useful hereininclude those manufactured by SkySpring Nanomaterials, Inc., which islisted below.

Metals and Non-Metal Elements Ag, 99.95%, 100 nm Ag, 99.95%, 20-30 nm

Ag, 99.95%, 20-30 nm, PVP coated

Ag, 99.9%, 50-60 nm

Ag, 99.99%, 30-50 nm, oleic acid coatedAg, 99.99%, 15 nm, 10 wt %, self-dispersibleAg, 99.99%, 15 nm, 25 wt %, self-dispersible

Al, 99.9%, 18 nm Al, 99.9%, 40-60 nm Al, 99.9%, 60-80 nm

Al, 99.9%, 40-60 nm, low oxygen

Au, 99.9%, 100 nm

Au, 99.99%, 15 nm, 10 wt %, self-dispersible

B, 99.9999% B, 99.999% B, 99.99% B, 99.9% B, 99.9%, 80 nm Diamond, 95%,3-4 nm Diamond, 93%, 3-4 nm Diamond, 55-75%, 4-15 nm Graphite, 93%, 3-4nm Super Activated Carbon, 100 nm Co, 99.8%, 25-30 nm Cr, 99.9%, 60-80nm Cu, 99.5%, 300 nm Cu, 99.5%, 500 nm Cu, 99.9%, 25 nm Cu, 99.9%, 40-60nm Cu, 99.9%, 60-80 nm

Cu, 5-7 nm, dispersion, oil soluble

Fe, 99.9%, 20 nm Fe, 99.9%, 40-60 nm Fe, 99.9%, 60-80 nm

Carbonyl-Fe, micro-sized

Mo, 99.9%, 60-80 nm Mo, 99.9%, 0.5-0.8 μm

Ni, 99.9%, 500 nm (adjustable)

Ni, 99.9%, 20 nm

Ni coated with carbon, 99.9%, 20 nm

Ni, 99.9%, 40-60 nm Ni, 99.9%, 60-80 nm Carbonyl-Ni, 2-3 μm Carbonyl-Ni,4-7 μm Carbonyl-Ni—Al (Ni Shell, Al Core) Carbonyl-Ni—Fe Alloy

Pt, 99.95%, 5 nm, 10 wt %, self-dispersible

Si, Cubic, 99%, 50 nm

Si, Polycrystalline, 99.99995%, lumps

Sn, 99.9%, <100 nm Ta, 99.9%, 60-80 nm Ti, 99.9%, 40-60 nm Ti, 99.9%,60-80 nm W, 99.9%, 40-60 nm W, 99.9%, 80-100 nm Zn, 99.9%, 40-60 nm Zn,99.9%, 80-100 nm Metal Oxides AlOOH, 10-20 nm, 99.99%

Al₂O₃ alpha, 98+%, 40 nmAl₂O₃ alpha, 99.999%, 0.5-10 μmAl₂O₃ alpha, 99.99%, 50 nmAl₂O₃ alpha, 99.99%, 0.3-0.8 μmAl₂O₃ alpha, 99.99%, 0.8-1.5 μmAl₂O₃ alpha, 99.99%, 1.5-3.5 μmAl₂O₃ alpha, 99.99%, 3.5-15 μmAl₂O₃ gamma, 99.9%, 5 nmAl₂O₃ gamma, 99.99%, 20 nmAl₂O₃ gamma, 99.99%, 0.4-1.5 μmAl₂O₃ gamma, 99.99%, 3-10 μmAl₂O₃ gamma, ExtrudateAl₂O₃ gamma, Extrudate

Al(OH)₃, 99.99%, 30-100 nm Al(OH)₃, 99.99%, 2-10 μm

Aluminium Iso-Propoxide (AIP), C₉H₂₁O₃Al, 99.9%

AlN, 99%, 40 nm BaTiO₃, 99.9%, 100 nm BBr₃, 99.9%

B₂O₃, 99.5%, 80 nm

BN, 99.99%, 3-4 μm BN, 99.9%, 3-4 μm B₄C, 99%, 50 nm

Bi₂O₃, 99.9%, <200 nm

CaCO₃, 97.5%, 15-40 nm CaCO₃, 15-40 nm

Ca₃(PO₄)₂, 20-40 nmCa₁₀(PO₄)₆(OH)₂, 98.5%, 40 nm

CeO₂, 99.9%, 10-30 nm CoO, <100 nm

Co₂O₃, <100 nmCo₃O₄, 50 nm

CuO, 99+%, 40 nm

Er₂O₃, 99.9%, 40-50 nmFe₂O₃ alpha, 99%, 20-40 nmFe₂O₃ gamma, 99%, 20-40 nmFe₃O₄, 98+%, 20-30 nmFe₃O₄, 98+%, 10-20 nmGd₂O₃, 99.9%<100 nm

HfO₂, 99.9%, 100 nm

In₂O₃:SnO₂=90:10, 20-70 nmIn₂O₃, 99.99%, 20-70 nm

In(OH)₃, 99.99%, 20-70 nm LaB₆, 99.0%, 50-80 nm

La₂O₃, 99.99%, 100 nm

LiFePO₄, 40 nm MgO, 99.9%, 10-30 nm MgO, 99%, 20 nm MgO, 99.9%, 10-30 nmMg(OH)₂, 99.8%, 50 nm

Mn₂O₃, 98+%, 40-60 nm

MoCl₅, 99.0%

Nd₂O₃, 99.9%, <100 nm

NiO, <100 nm

Ni₂O₃, <100 nmSb₂O₃, 99.9%, 150 nm

SiO₂, 99.9%, 20-60 nm

SiO₂, 99%, 10-30 nm, treated with Silane Coupling AgentsSiO₂, 99%, 10-30 nm, treated with HexamethyldisilazaneSiO₂, 99%, 10-30 nm, treated with Titanium EsterSiO₂, 99%, 10-30 nm, treated with SilanesSiO₂, 10-20 nm, modified with amino group, dispersibleSiO₂, 10-20 nm, modified with epoxy group, dispersibleSiO₂, 10-20 nm, modified with double bond, dispersibleSiO₂, 10-20 nm, surface modified with double layer, dispersibleSiO₂, 10-20 nm, surface modified, super-hydrophobic & oleophilic,dispersibleSiO₂, 99.8%, 5-15 nm, surface modified, hydrophobic & oleophilic,dispersibleSiO₂, 99.8%, 10-25 nm, surface modified, super-hydrophobic, dispersibleSiC, beta, 99%, 40 nmSiC, beta, whisker, 99.9%Si₃N₄, amorphous, 99%, 20 nmSi₃N₄ alpha, 97.5-99%, fiber, 100 nm×800 nm

SnO₂, 99.9%, 50-70 nm

ATO, SnO₂:Sb₂O₃=90:10, 40 nmTiO₂ anatase, 99.5%, 5-10 nm

TiO₂ Rutile, 99.5%, 10-30 nm

TiO₂ Rutile, 99%, 20-40 nm, coated with SiO₂, highly hydrophobicTiO₂ Rutile, 99%, 20-40 nm, coated with SiO₂/Al₂O₃TiO₂ Rutile, 99%, 20-40 nm, coated with Al₂O₃, hydrophilicTiO₂ Rutile, 99%, 20-40 nm, coated with SiO₂/Al₂O₃/Stearic AcidTiO₂ Rutile, 99%, 20-40 nm, coated with Silicone Oil, hydrophobic

TiC, 99%, 40 nm TiN, 97+%, 20 nm WO₃, 99.5%, <100 nm WS₂, 99.9%, 0.8 μmWCl₆, 99.0%

Y₂O₃, 99.995%, 30-50 nm

ZnO, 99.8%, 10-30 nm

ZnO, 99%, 10-30 nm, treated with silane coupling agentsZnO, 99%, 10-30 nm, treated with stearic acidZnO, 99%, 10-30 nm, treated with silicone oil

ZnO, 99.8%, 200 nm ZrO₂, 99.9%, 100 nm ZrO₂, 99.9%, 20-30 nm ZrO₂-3Y,99.9%, 0.3-0.5 um ZrO₂-3Y, 25 nm ZrO₂-5Y, 20-30 nm ZrO₂-8Y, 99.9%,0.3-0.5 μm ZrO₂-8Y, 20 nm ZrC, 97+%, 60 nm

In one aspect, the filler is nanosilica. Nanosilica is commerciallyavailable from multiple sources in a broad size range. For example,aqueous Nexsil colloidal silica is available in diameters from 6-85 nmfrom Nyacol Nanotechnologies, Inc. Amino-modified nanosilica is alsocommercially available, from Sigma Aldrich for example, but in anarrower range of diameters than unmodified silica. Nanosilica does notcontribute to the opacity of the coacervate, which is an importantattribute of the adhesives and glues produced therefrom.

In another aspect, the filler can be composed of calcium phosphate. Inone aspect, the filler can be hydroxyapatite, which has the formulaCa₅(PO₄)₃OH. In another aspect, the filler can be a substitutedhydroxyapatite. A substituted hydroxyapatite is hydroxyapatite with oneor more atoms substituted with another atom. The substitutedhydroxyapatite is depicted by the formula M₅X₃Y, where M is Ca, Mg, Na;X is PO₄ or CO₃; and Y is OH, F, Cl, or CO₃. Minor impurities in thehydroxyapatite structure may also be present from the following ions:Zn, Sr, Al, Pb, Ba. In another aspect, the calcium phosphate comprises acalcium orthophosphate. Examples of calcium orthophosphates include, butare not limited to, monocalcium phosphate anhydrate, monocalciumphosphate monohydrate, dicalcium phosphate dihydrate, dicalciumphosphate anhydrous, octacalcium phosphate, beta tricalcium phosphate,alpha tricalcium phosphate, super alpha tricalcium phosphate,tetracalcium phosphate, amorphous tricalcium phosphate, or anycombination thereof. In other aspects, the calcium phosphate can alsoinclude calcium-deficient hydroxyapatite, which can preferentiallyadsorb bone matrix proteins.

In certain aspects, the filler can be functionalized with one or moreamino or activated ester groups. In this aspect, the filler can becovalently attached to the polycation or polyanion. For example,aminated silica can be reacted with the polyanion possessing activatedester groups to form new covalent bonds.

In other aspects, the filler can be modified to produce charged groupssuch that the filler can form electrostatic bonds with the coacervates.For example, aminated silica can be added to a solution and the pHadjusted so that the amino groups are protonated and available forelectrostatic bonding.

In one aspect, the reinforcing component can be micelles or liposomes.In general, the micelles and liposomes used in this aspect are differentfrom the micelles or liposomes used as polycations and polyanions forpreparing the coacervate. The micelles and liposomes can be preparedfrom the nonionic, cationic, or anionic surfactants described above. Thecharge of the micelles and liposomes can vary depending upon theselection of the polycation or polyanion as well as the intended use ofthe coacervate. In one aspect, the micelles and liposomes can be used tosolubilize hydrophobic compounds such pharmaceutical compounds. Thus, inaddition to be used as adhesives, the adhesive complex coacervatesdescribed herein can be effective as a bioactive delivery device.

V. Initiators

In certain aspects, the in situ solidifying complex coacervate alsoincludes one or more initiators entrapped in the coacervate. Examples ofinitiators useful herein include a thermal initiator, a chemicalinitiator, or a photoinitiator to promote crosslinking amongst thedifferent components in the complex coacervate composition.

Examples of photoinitiators include, but are not limited to a phosphineoxide, peroxides, peracids, azide compounds, α-hydroxyketones, orα-aminoketones. In one aspect, the photoinitiator includes, but is notlimited to, camphorquinone, benzoin methyl ether,1-hydroxycyclohexylphenyl ketone, or Darocure® or Irgacure® types, forexample Darocure® 1173 or Irgacure® 2959. The photoinitiators disclosedin European Patent No. 0632329, which are incorporated by reference, canbe used herein. In other aspects, the photoinitiator is a water-solublephotoinitiator including, but not limited to, riboflavin, eosin, eosiny, and rose Bengal.

In one aspect, the initiator has a positively charged functional group.Examples include2,2′-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]-dihydrochloride;2,2′-azobis[2-(2-imidazolin-2-yl) propane]dihydrochloride;2,2′-azobis[2-(2-imidazo-lin-2-yl)propane]disulfate dehydrate;2,2′-azobis(2-methylpropionamidine)dihydrochloride;2,2′-azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane]dihydrochloride;azobis {2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride;2,2′-azobis(1-imino-1-pyrrolidino-2-ethylpropane)dihydrochloride andcombinations thereof.

In another aspect, the initiator is an oil soluble initiator. In oneaspect, the oil soluble initiator includes organic peroxides or azocompounds.

Examples of organic peroxides include ketone peroxides, peroxyketals,hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates,peroxyesters, and the like. Some specific non-limiting examples oforganic peroxides that can be used as the oil soluble initiator include:lauroyl peroxide, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, t-butylperoxylaurate,t-butylperoxyisopropylmonocarbonate,t-butylperoxy-2-ethylhexylcarbonate,di-t-butylperoxyhexahydro-terephthalate, dicumyl peroxide,2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di-t-butyl peroxide,t-butylperoxy-2-ethylhexanoate,bis(4-t-butylcyclohexyl)peroxydi-carbonate,t-amylperoxy-3,5,5-trimethylhexanoate,1,1-di(t-amylperoxy)-3,3,5-trimethylcyclohexane, benzoyl-peroxide,t-butylperoxyacetate, and the like.

Some specific non-limiting examples of azo compounds that can be used asthe oil soluble initiator include: 2,2′-azobis-isobutyronitrile,2,2′-azobis-2,4-dimethylvaleronitrile,1,1′-azobis-1-cyclohexane-carbonitrile, dimethyl-2,2′-azobisisobutyrate,1,1′-azobis-(1-acetoxy-1-phenylethane), 4,4′-azobis(4-cyanopentanoicacid) and its soluble salts (e.g., sodium, potassium), and the like.

In one aspect, the initiator is a water-soluble initiator including, butnot limited to, potassium persulfate, ammonium persulfate, sodiumpersulfate, and mixtures thereof. In another aspect, the initiator is anoxidation-reduction initiator such as the reaction product of theabove-mentioned persulfates and reducing agents such as sodiummetabisulfite and sodium bisulfite; and 4,4′-azobis(4-cyanopentanoicacid) and its soluble salts (e.g., sodium, potassium).

In certain aspects, multiple initiators can be used to broaden theabsorption profile of the initiator system in order to increase theinitiation rate. For example, two different photoinitiators can beemployed that are activated by different wavelengths of light. Inanother aspect, a co-initiator can be used in combination with any ofthe initiators described herein. In one aspect, the co-initiator is2-(diethylamino)ethyl acrylate, 2-(dimethylamino)ethyl acrylate,2-(dimethylamino)ethyl benzoate, 2-(dimethylamino)ethyl methacrylate,2-ethylhexyl 4-(dimethylamino)benzoate, 3-(dimethylamino)propylacrylate, 4,4′-bis(diethylamino)benzophenone, or4-(diethylamino)benzophenone.

In certain aspects, the initiator and/or co-initiator are covalentlyattached to the polycation and/or polyanion. For example, the initiatorand/or co-initiator can be copolymerized with monomers used to make thepolycation and/or polyanion. In one aspect, the initiators andco-initiators possess polymerizable olefinic groups such as acrylate andmethacrylate groups (e.g., see examples of co-initiators above) that canbe copolymerized with monomers described above used to make thepolycation and polyanion. In another aspect, the initiators can bechemically grafted onto the backbone of the polycation and polyanion.Thus, in these aspects, the photoinitiator and/or co-initiator arecovalently attached to the polymer and pendant to the polymer backbone.This approach will simply formulation and possibly enhance storage andstability.

In other aspects, the initiator and/or co-initiator areelectrostatically associated into the fluid complex coacervate.

VI. Multivalent Cations

The in situ solidifying complex coacervates can optionally contain oneor more multivalent cations (i.e., cations having a charge of +2 orgreater). In one aspect, the multivalent cation can be a divalent cationcomposed of one or more alkaline earth metals. For example, the divalentcation can be a mixture of Ca⁺² and Mg⁺². In other aspects, transitionmetal ions with a charge of +2 or greater can be used as the multivalentcation. The concentration of the multivalent cations can determine therate and extent of coacervate formation. Not wishing to be bound bytheory, weak cohesive forces between particles in the fluid may bemediated by multivalent cations bridging excess negative surfacecharges. The amount of multivalent cation used herein can vary. In oneaspect, the amount is based upon the number of anionic groups andcationic groups present in the polyanion and polycation.

Preparation of In Situ Solidifying Complex Coacervates

The synthesis of the in situ solidifying complex coacervates describedherein can be performed using a number of techniques and procedures.Exemplary techniques for producing the coacervates are provided in theExamples. In one aspect, the polycation and polyanion are mixed asdilute solutions. Upon mixing, when the polycation and polyanionassociate they condense into a fluid/liquid phase at the bottom of amixing chamber (e.g., a tube) to produce a condensed phase. Thecondensed phase (i.e., fluid complex coacervate) is separated and usedas the in situ solidifying complex coacervate.

In one aspect, an aqueous solution of polycation is mixed with anaqueous solution of polyanion such that the positive/negative chargeratio of the polycation to the polyanion is from 4 to 0.25, 3 to 0.25, 2to 0.25, 1.5 to 0.5, 1.10 to 0.95, 1 to 1. Depending upon the number ofcharged groups on the polycation and polyanion, the amount of polycationand polyanion can be varied in order to achieve specificpositive/negative charge ratios. The in situ solidifying complexcoacervate contains water, wherein the amount of water is from 20% to80% by weight of the composition.

The pH of the solution containing the polycation, polyanion, and themonovalent salt can vary in order to optimize complex coacervateformation. In one aspect, the pH of the composition containing the insitu solidifying complex coacervate is from 6 to 9, 6.5 to 8.5, 7 to 8,or 7 to 7.5. In another aspect, the pH of the composition is 7.2 (i.e.,physiological pH).

The amount of the monovalent salt that is present in the in situsolidifying complex coacervate can vary depending upon the concentrationof the monovalent salt in the environment at which the in situsolidifying complex coacervate is introduced. This is demonstrated inthe Examples and FIGS. 10A and 10B. In general, the concentration of themonovalent salt in the complex coacervate is greater than theconcentration of the monovalent salt in the environment. For example,the concentration of Na and KCl under physiological conditions is about150 mM. Therefore, if the in situ solidifying complex coacervate is tobe administered to a human subject, the concentration of the monovalentsalt present in the in situ solidifying complex coacervate would begreater than 150 mM. In one aspect, the monovalent salt that is presentin the in situ solidifying complex coacervate is at a concentration from0.5 M to 2.0 M. In another aspect, the concentration of the monovalentsalt is 0.5 to 1.8, 0.5 to 1.6, 0.5 to 1.4, or 0.5 to 1.2. In anotheraspect, the concentration of the monovalent salt in the complexcoacervate is 1.5 to 2, 1.5 to 3, 1.5 to 4, 1.5 to 5, 1.5 to 6, 1.5 to7, 1.5 to 8, 1.5 to 9 or 1.5 to 10 times greater than the concentrationof the monovalent salt in the aqueous environment.

In one aspect, the monovalent salt can be sodium chloride or potassiumchloride or a mixture. In other aspects, the in situ solidifying complexcoacervate can be formulated in hypertonic saline solutions that can beused for parenteral or intravenous administration or by injection to asubject. In one aspect, the in situ solidifying complex coacervate canbe formulated in Ringer's dextrose, dextrose and sodium chloride,lactated Ringer's, or other buffered saline solutions that can be safelyadministered to a subject, wherein the saline concentration has beenadjusted so that it is greater than saline concentration atphysiological conditions.

Kits

The polycations and polyanions described herein can be stored as drypowders for extended periods of time. This feature is very useful forpreparing the coacervates and ultimately the adhesives when desired.Thus, described herein are kits for making the in situ solidifyingcomplex coacervates and adhesives described herein. In one aspect, thekit comprises (1) at least one polyanion, (2) at least one polycation,wherein the positive/negative charge ratio of the polycation to thepolyanion is from 0.25 to 4, and (3) an aqueous solution comprising amonovalent salt at a concentration from 0.5 M to 2.0 M. The kits canalso include additional components as described herein (e.g.,reinforcing components, initiators, bioactive agents, contrast agents,etc.).

When stored as dried powders, water can be added to the polycationand/or polyanion to produce the coacervate. In one aspect, prior tolyophilizing the polycation and polyanion in order to produce a drypowder, the pH of the polycation and polyanion can be adjusted such thatwhen they are admixed in water the desired pH is produced without theaddition of acid or base. For example, excess base can be present in thepolycation powder which upon addition of water adjusts the pHaccordingly.

In another aspect, the in situ solidifying complex coacervate can beloaded in a syringe for future. Due to the stability of the in situsolidifying complex coacervate, a sterilized solution of the complexcoacervate can be stored in the syringe for extended periods of time andused as needed.

Applications of the In Situ Solidifying Complex Coacervates

The in situ solidifying complex coacervates and adhesives describedherein have numerous benefits and applications where it is desirable toproduce adhesives and coatings in an aqueous environment. As discussedabove, the in situ solidifying complex coacervates are fluids with lowviscosity and are readily injectable via a narrow gauge device, syringe,catheter, needle, cannula, or tubing. The in situ solidifying complexcoacervates are water-borne eliminating the need for potentially toxicsolvents.

The in situ solidifying complex coacervates described herein are fluidsat ionic strengths higher than the ionic strength of the applicationsite, but insoluble ionic hydrogels at the ionic strength of theapplication site. When the fluid, high ionic strength complexcoacervates are introduced into a lower ionic strength application site,the complex coacervates forms a solid or gel in situ at the applicationsite as the salt concentration in the complex coacervate equilibrates tothe application site salt concentration. The solid or gel that issubsequently produced is a non-fluid, water insoluble material.

The ionic concentration at the application site can vary depending uponthe ionic concentration of the in situ solidifying complex coacervate.In one aspect, the application site has one or more monovalent salts,where the concentration of the monovalent salts is less than 500 mM, orfrom 150 mM to less than 500 mM. In another aspect, the ionicconcentration of the monovalent salt at the application site is from 150mM to 600 mM and the concentration of the monovalent salt of the complexcoacervate composition is greater than 600 mM to 2 M.

The in situ solidifying complex coacervates can form solids or gels insitu under physiological conditions. The physiological ionic strength isapproximately 300 mOsm/L. Thus, when in situ solidifying complexcoacervates having an ionic strength greater than 300 mOsm/L areintroduced to a subject (e.g., injected into a mammal), the fluidcomplex coacervate is converted to an adhesive solid or gel at the siteof application. Thus, the in situ solidifying complex coacervatesdescribed herein have numerous medical and biological applications,which are described in detail below.

In one aspect, the in situ solidifying complex coacervates can includeone or more contrast agents. Upon administration of the in situsolidifying complex coacervates to the subject, the physician canmonitor precisely the position of the adhesive gel or solid that isproduced in situ. Contrast agents known in the art can be used herein.In one aspect, the contrast agent can be admixed with the polycation andpolyanion. For example, metal particles such as tantalum powder or goldcan be used. Alternatively soluble iodine complexes can be used as thecontrast agent. The contrast agent can be detected using techniquesknown in the art including X-ray, NMR imaging, ultrasound, andfluoroscopes.

In other aspect, a visualization agent can be used to visibly detect theposition of the complex coacervate. An example of this is depicted inFIG. 6B, where fluorescein is covalently bonded to a syntheticpolyguanidinyl polymer (i.e., a polycation). Thus, in one aspect,polymerizable monomers with a contrast or visualization agent covalentlybonded to it can be polymerized with other monomers to producepolycations and polyanions useful herein medical and biologicalapplications.

In one aspect, the in situ solidifying complex coacervates and adhesivesolids and gels produced therefrom can be used to reduce or inhibitblood flow in a blood vessel of a subject. In this aspect, the adhesivesolid or gel produced from the fluid complex coacervate creates anartificial embolus within the vessel. Thus, the fluid complexcoacervates described herein can be used as synthetic embolic agents. Inthis aspect, the in situ solidifying complex coacervate is injected intothe vessel followed by formation of the adhesive solid or gel in orderto partially or completely block the vessel. This method has numerousapplications including hemostasis or the creation of an artificialembolism to inhibit blood flow to a tumor, aneurysm, varicose vein, anarteriovenous malformation, an open or bleeding wound, or other vasculardefects.

As discussed above, the fluid complex coacervates can be used assynthetic embolic agents. However, in other aspects, the fluid complexcoacervate described herein can include one or more additional embolicagents. Embolic agents commercially-available are microparticles usedfor embolization of blood vessels. The size and shape of themicroparticles can vary. In one aspect, the microparticles can becomposed of polymeric materials. An example of this is Bearin™ nsPVAparticles manufactured by Merit Medical Systems, Inc., which arecomposed of polyvinyl alcohol ranging is size from 45 μm to 1,180 μm. Inanother aspect, the embolic agent can be a microsphere composed of apolymeric material. Examples of such embolic agents include Embosphere®Microspheres, which are made from trisacryl cross linked with gelatinranging is size from 40 μm to 1,200 μm; HepaSphere™ Microspheres(spherical, hydrophilic microspheres made from vinyl acetate and methylacrylate) ranging is size from 30 μm to 200 μm; and QuadraSphere®Microspheres (spherical, hydrophilic microspheres made from vinylacetate and methyl acrylate) ranging is size from 30 μm to 200 μm, allof which are manufactured by Merit Medical Systems, Inc. In anotheraspect, the microsphere can be impregnated with one or more metals thatcan be used as a contrast agent. An example of this is EmboGold®Microspheres manufactured by Merit Medical Systems, Inc., which are madefrom trisacryl cross linked with gelatin impregnated with 2% elementalgold ranging is size from 40 μm to 1,200 μm.

In another aspect, the fluid complex coacervate includes a contrastagent for visualizing the location of the solid or gel that is producedin the subject from the fluid complex coacervate. The contrast agentsand methods for visualizing discussed above can be used in thisembodiment. In one aspect, the contrast agent can be tantalum particleshaving a particle size from 0.5 μm to 50 μm, 1 μm to 25 μm, 1 μm to 10μm, or 1 μm to 5 μm. In another aspect, contrast agent is tantalumparticles in the amount of 10% to 60%, 20% to 50%, or 20% to 40%.

In the case of embolic applications, the addition of components such ascontrast agents or embolic agents can affect the viscosity of the fluidcomplex coacervate and administration to a subject. For example, a fluidcomplex coacervate containing a contrast agent such as titaniumparticles will be more viscous at low shear rates than the same fluidcomplex coacervate that does not include the titanium particles (see forexample FIG. 9). Furthermore, the viscosity of the fluid complexcoacervate can recover at low shear rates. Reversible shear thinningallows the viscous fluid complex coacervates described herein to beinjected through a long narrow catheter with low force, and as the shearrate decreases to zero at the catheter exit, the viscosity of thecomplex coacervate increases to prevent it from flowing away from theapplication site. This allows precise control while injecting thecomposition.

In one aspect, the in situ solidifying complex coacervates and adhesivesolids and gels produced therefrom can be used to reinforce the innerwall of a blood vessel in the subject. The in situ solidifying complexcoacervate can be introduced into the vessel at a sufficient amount tocoat the inner lining of the vessel so that the vessel is not blocked.For example, the in situ solidifying complex coacervate can be injectedinto a vessel where there is an aneurysm. Here, the in situ solidifyingcomplex coacervate reduce or prevents the rupture of an aneurysm. In oneaspect, the fluid complex coacervate can include a contrast agent. Thecontrast agents and methods for visualizing discussed above can be usedin this embodiment.

In one aspect, the in situ solidifying complex coacervates and adhesivesolids and gels produced therefrom can be used to close or seal apuncture in a blood vessel in the subject. In one aspect, the in situsolidifying complex coacervate can be injected into a vessel at asufficient amount to close or seal the puncture from within the vesselso that the vessel is not blocked. In another embodiment, the in situsolidifying complex coacervate can be applied to puncture on theexterior surface of the vessel to seal the puncture. In one aspect, thefluid complex coacervate can include a contrast agent. The contrastagents and methods for visualizing discussed above can be used in thisembodiment.

In one aspect, the in situ solidifying complex coacervates and adhesivesolids and gels produced therefrom can be used to repair a number ofdifferent bone fractures and breaks. The adhesive solids and gels uponformation adhere to bone (and other minerals) through severalmechanisms. The surface of the bone's hydroxyapatite mineral phase(Ca₅(PO₄)₃(OH)) is an array of both positive and negative charges. Thenegative groups present on the polyanion (e.g., phosphate groups) caninteract directly with the positive surface charges or it can be bridgedto the negative surface charges through the cationic groups on thepolycation and/or multivalent cations. Likewise, direct interaction ofthe polycation with the negative surface charges would contribute toadhesion. Alternatively, oxidized crosslinkers can couple tonucleophilic sidechains of bone matrix proteins.

Examples of such breaks include a complete fracture, an incompletefracture, a linear fracture, a transverse fracture, an oblique fracture,a compression fracture, a spiral fracture, a comminuted fracture, acompacted fracture, or an open fracture. In one aspect, the fracture isan intra-articular fracture or a craniofacial bone fracture. Fracturessuch as intra-articular fractures are bony injuries that extend into andfragment the cartilage surface. The adhesive solids and gels producedfrom the in situ solidifying complex coacervates may aid in themaintenance of the reduction of such fractures, allow less invasivesurgery, reduce operating room time, reduce costs, and provide a betteroutcome by reducing the risk of post-traumatic arthritis.

In other aspects, the in situ solidifying complex coacervates andadhesive solids and gels produced therefrom can be used to join smallfragments of highly comminuted fractures. In this aspect, small piecesof fractured bone can be adhered to an existing bone. It is especiallychallenging to maintain reduction of the small fragments by drillingthem with mechanical fixators. The smaller and greater the number offragments the greater the problem. In one aspect, the in situsolidifying complex coacervates may be injected in small volumes tocreate spot welds as described above in order to fix the fracture ratherthan filling the entire crack. The small biocompatible spot welds wouldminimize interference with healing of the surrounding tissue and wouldnot necessarily have to be biodegradable. In this respect it would besimilar to permanently implanted hardware.

The in situ solidifying complex coacervates and adhesive solids and gelsproduced therefrom have numerous dental applications. For example, thein situ solidifying complex coacervates and adhesive solids and gelsproduced therefrom can be used to seal breaks or cracks in teeth, forsecuring crowns, or allografts, or seating implants and dentures. The insitu solidifying complex coacervate can be applied to a specific pointsin the mouth (e.g., jaw, sections of a tooth) followed by attaching theimplant to the substrate and subsequent curing.

In other aspects, the in situ solidifying complex coacervates andadhesive solids and gels produced therefrom can adhere a substrate tobone other tissues such as, for example, cartilage, ligaments, tendons,soft tissues, organs, and synthetic derivatives of these materials. Forexample, implants made from titanium oxide, stainless steel, or othermetals are commonly used to repair fractured bones. The in situsolidifying complex coacervate can be applied to the metal substrate,the bone, or both prior to adhering the substrate to the bone. In otheraspects, the substrate can be a fabric (e.g., an internal bandage), atissue graft, a patch, or a wound healing material. Thus, in addition tobonding bone fragments, the in situ solidifying complex coacervates andadhesive solids and gels produced therefrom can facilitate the bondingof substrates to bone, which can facilitate bone repair and recovery.Using the fluid coacervate complexes and spot welding techniquesdescribed herein, the in situ solidifying complex coacervates andadhesive solids and gels produced therefrom can be used to positionbiological scaffolds in a subject. Small adhesive tacks composed of theadhesive complex coacervates described herein would not interfere withmigration of cells or transport of small molecules into or out of thescaffold. In certain aspects, the scaffold can contain one or more drugsthat facilitate growth or repair of the bone and tissue. In otheraspects, the scaffold can include drugs that prevent infection such as,for example, antibiotics. For example, the scaffold can be coated withthe drug or, in the alternative, the drug can be incorporated within thescaffold so that the drug elutes from the scaffold over time.

It is also contemplated that the adhesive gels and solids produced fromthe in situ solidifying complex coacervates described herein canencapsulate, scaffold, seal, or hold one or more bioactive agents. Thebioactive agents can be any drug including, but not limited to,antibiotics, pain relievers, immune modulators, growth factors, enzymeinhibitors, hormones, mediators, messenger molecules, cell signalingmolecules, receptor agonists, oncolytics, chemotherapy agents, orreceptor antagonists. The agent may also be autologous or homologous(allogeneic) cells, platelet rich plasma (PRP), or other like tissue.

In another aspect, the bioactive agent can be a nucleic acid. Thenucleic acid can be an oligonucleotide, deoxyribonucleic acid (DNA),ribonucleic acid (RNA), or peptide nucleic acid (PNA). The nucleic acidof interest can be nucleic acid from any source, such as a nucleic acidobtained from cells in which it occurs in nature, recombinantly producednucleic acid, or chemically synthesized nucleic acid. For example, thenucleic acid can be cDNA or genomic DNA or DNA synthesized to have thenucleotide sequence corresponding to that of naturally-occurring DNA.The nucleic acid can also be a mutated or altered form of nucleic acid(e.g., DNA that differs from a naturally occurring DNA by an alteration,deletion, substitution or addition of at least one nucleic acid residue)or nucleic acid that does not occur in nature.

In other aspects, the bioactive agent is used in bone treatmentapplications. For example, the bioactive agent can be bone morphogeneticproteins (BMPs) and prostaglandins. When the bioactive agent is used totreat osteoporosis, bioactive agents known in the art such as, forexample, bisphonates, can be delivered locally to the subject by the insitu solidifying complex coacervates and adhesive solids and gelsproduced therefrom.

In certain aspects, the filler used to produce the in situ solidifyingcomplex coacervate can also possess bioactive properties. For example,when the filler is a silver particle, the particle can also behave as ananti-microbial agent. The rate of release can be controlled by theselection of the materials used to prepare the complex, as well as thecharge of the bioactive agent if the agent has ionizable groups. Thus,in this aspect, the adhesive solid or gel produced from the in situsolidifying complex coacervate can perform as a localized controlleddrug release depot. It may be possible to simultaneously fix tissue andbones as well as deliver bioactive agents to provide greater patientcomfort, accelerate bone healing, and/or prevent infections.

The adhesive complex coacervates and adhesives produced therefrom can beused in a variety of other surgical procedures. For example, the in situsolidifying complex coacervates can be applied as a covering to a woundcreated by the surgical procedure to promote wound healing and preventinfection. In one aspect, the in situ solidifying complex coacervatesand adhesive solids and gels produced therefrom can be used to treatocular wounds caused by trauma or by the surgical procedures. In oneaspect, the in situ solidifying complex coacervates and adhesivesproduced therefrom can be used to repair a corneal or schlerallaceration in a subject. In other aspects, the in situ solidifyingcomplex coacervates can be used to facilitate healing of ocular tissuedamaged from a surgical procedure (e.g., glaucoma surgery or a cornealtransplant). The methods disclosed in U.S. Published Application No.2007/0196454, which are incorporated by reference, can be used to applythe coacervates described herein to different regions of the eye.

The in situ solidifying complex coacervates and adhesive solids and gelsproduced therefrom can be used to seal the junction between skin and aninserted medical device such as catheters, electrode leads, needles,cannulae, osseo-integrated prosthetics, and the like. Here, uponinsertion and/or removal of the medical device the fluid complexcoacervate is applied to the junction between the skin of the subjectand the inserted medical device in order to seal the junction. Thus, thefluid complex coacervate prevent infection at the entry site when thedevice is inserted in the subject and subsequently forms a solid or gel.In other aspects, the in situ solidifying complex coacervates can beapplied to the entry site of the skin after the device has been removedin order to expedite wound healing and prevent further infection.

In another aspect, the in situ solidifying complex coacervates andadhesive solids and gels produced therefrom can be used to prevent orreduce the proliferation of tumor cells during tumor biopsy. The methodinvolves back-filling the track produced by the biopsy needle with thein situ solidifying complex coacervates upon removal of the biopsyneedle. In one aspect, the in situ solidifying complex coacervatesincludes an anti-proliferative agent that will prevent or reduce thepotential proliferation of malignant tumor cells to other parts of thesubject during the biopsy.

In another aspect, the in situ solidifying complex coacervates andadhesive solids and gels produced therefrom can be used to close or seala puncture in an internal tissue or membrane. In certain medicalapplications, internal tissues or membranes are punctured, whichsubsequently have to be sealed in order to avoid additionalcomplications. Alternatively, the in situ solidifying complexcoacervates and adhesive solids and gels produced therefrom can be usedto adhere a scaffold or patch to the tissue or membrane in order to sealthe tissue, prevent further damage and facilitate wound healing.

In another aspect, the in situ solidifying complex coacervates andadhesive solids and gels produced therefrom can be used to seal afistula in a subject. A fistula is an abnormal connection between anorgan, vessel, or intestine and another structure such as, for example,skin. Fistulas are usually caused by injury or surgery, but they canalso result from an infection or inflammation. Fistulas are generally adisease condition, but they may be surgically created for therapeuticreasons. In other aspects, the in situ solidifying complex coacervatesand adhesive solids and gels produced therefrom can prevent or reduceundesirable adhesion between two tissues in a subject, where the methodinvolves contacting at least one surface of the tissue with the in situsolidifying complex coacervate. In one aspect, the fistula is anenterocutaneous fistula (ECF). ECF is an abnormal connection thatdevelops between the intestinal tract or stomach and the skin. As aresult, contents of the stomach or intestines leak through to the skin.Most ECFs occur after bowel surgery.

In certain aspects, after the adhesive solid or gel has been producedfrom the in situ solidifying complex coacervates, the adhesive solid orgel can be subsequently cured by covalently crosslinking the polycationand/or polyanion having crosslinkable groups in the solid or gel.Depending upon the selection of starting materials, varying degrees ofcrosslinking can occur throughout the coacervate during curing. Theadhesive gel can be exposed to heat or light in order to facilitatecrosslinking. Any of the initiators described herein can be included inthe in situ solidifying complex coacervates to facilitate covalentcrosslinking.

In addition to medical biological application, the in situ complexcoacervates can be incorporated in a number of other articles andcompositions that contain water or that will be exposed to an aqueousenvironment. For example, the in situ solidifying complex coacervatescan be used as underwater coating or paint. In one aspect, the in situsolidifying complex coacervate can be applied to a submerged surface ina freshwater or marine environment and would rapidly solidify to form aprotective coating on the surface. For example, the in situ solidifyingcomplex coacervates can be used in marine applications, where themonovalent salt concentration can be very high. Here, the monovalentsalt concentration in the in situ solidifying complex coacervate can beadjusted so that the in situ solidifying complex coacervate will form aninsoluble gel or solid when it comes into contact with seawater. In oneaspect, the adhesive gel or solid can be covalently crosslinked bynatural ambient light or by applying a light source. Crosslinking groupson the polycation and/or polyanion would allow the coating to becovalently crosslinked after application and gelation to increasehardness and improve strength and stability.

In other aspect, the other articles can include a cured adhesive complexcoacervate described herein. For example, the in situ solidifyingcomplex coacervate can be applied to a film substrate to create anadhesive tape. In this aspect, the application of the complex coacervateand ultimately the adhesive solid or gel is performed in an aqueousenvironment and does not require the removal of organic solventstypically used to prepare adhesive backings.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how thecompounds, compositions, and methods described and claimed herein aremade and evaluated, and are intended to be purely exemplary and are notintended to limit the scope of what the inventors regard as theirinvention. Efforts have been made to ensure accuracy with respect tonumbers (e.g., amounts, temperature, etc.) but some errors anddeviations should be accounted for. Unless indicated otherwise, partsare parts by weight, temperature is in ° C. or is at ambienttemperature, and pressure is at or near atmospheric. There are numerousvariations and combinations of reaction conditions, e.g., componentconcentrations, desired solvents, solvent mixtures, temperatures,pressures and other reaction ranges and conditions that can be used tooptimize the product purity and yield obtained from the describedprocess. Only reasonable and routine experimentation will be required tooptimize such process conditions.

Example 1 Protamine Methacrylation

Protamine sulfate from salmon sperm (MP Biomedical, cat#0210275280) wasdissolved in 150 mM NaCl solution at 50 mg/ml. The pH was adjusted to6.5 with NaOH. A ten-fold molar excess of glycidyl methacrylate wasadded dropwise while stirring at 20° C. The pH was adjusted to 6.5 every12 hrs. After 48 hrs the salmine was precipitated with 10-fold excessvolume of acetone. The precipitate was rinsed with acetone, dried, andre-dissolved in water. After dialysis for 48 hr the pH was adjusted to 7and the solution was lyophilized. Methacrylation on the C-terminalcarboxylate was verified by NMR spectroscopy.

Protamine Analogs: Synthetic Guanidinyl Polymers

Analogs of arginine-rich protamines were synthesized by free radicalcopolymerization of N-(3-methacrylamidopropyl) guanidinium chloride withacrylamide. The major advantages of synthetic polyguanidinium overnatural protamines are (1) the guanidinyl sidechain density, and therebythe polymer charge density, can be varied over a wide range to adjustgelation conditions, (2) the MW can be controlled and varied, (3) theguanidinyl monomer can be copolymerized with other monomers withsidechains that add additional functionality to the polymers, such ascrosslinking groups or fluorescent labels, and (4) synthetic acrylateprotamine analogs are non-degradable or slowly degradable forapplications in which biodegradability is not desirable.

FIG. 5 shows the reaction scheme for preparing an exemplary syntheticguanidinyl monomer. N-(3-methacrylamidopropyl)guanidinium chloride wassynthesized following published procedures. 1H-pyrazole-1-carboxamidinemonohydrochloride (12.3 g, 84 mmol) was added under Ar to a stirredsolution of N-(3-aminopropyl)methacrylamide hydrochloride (15 g, 84mmol), 4-methoxyphenol (150 mg) and N,N-diisopropylethylamine (38 mL,209 mmol) in DMF (85 mL, keeping the final concentration of thereactants 2M). The mixture was stirred at room temperature for 24 hunder Ar, then poured into diethylether (1200 mL). The resulting oilphase was separated from the supernatant and washed twice with asolution of acetonitrile (200 mL) and triethylamine (10 mL). Theresulting solid was washed with dichloromethane (300 mL) and dried undervacuum to yield 13.3 g (72%) of the product. ¹H NMR (400 MHz, DMSO-d₆) δppm 8.09 (s, 1H), 7.91 (s, 1H), 7.70-6.90 (br, 4H), 5.70 (s, 1H), 5.33(s, 1H), 3.16 (m, 4H), 1.87 (s, 3H), 1.65 (quin, 3H).

Polyguanidine (FIG. 6A) was synthesized by dissolvingN-(3-methacrylamidopropyl)guanidinium chloride, acrylamide, fluoresceinO-methacrylate and 4-cyano-4-(thiobenzoylthio)pentanoic acid in DMSO.After degassing for 30 min, the initiator azobisisobutyronitrile wasadded and the solution heated to 70° C. under Ar. After 40 h, thesolution was cooled, precipitated with acetone, and dissolved in water.Degassed for 30 min, added2,2′-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, and heated at70° C. overnight to remove the 4-cyano-4-(thiobenzoylthio)pentanoic acidRAFT agent. The polymer solution was purified by dialysis (MWCO-14,000)against dl water for 3 days, then lyophilized.

Methacrylamide sidechains were grafted onto polyguanidine (FIG. 6B) tofacilitate crosslinking of the polymers. Polyguanidium was dissolved inmethanol. Triethylamine and the inhibitor phenothiazine were added. Thesolution was cooled to 0° C. before addition of methacryloyl chloride.The reaction was removed from the ice bath and stirred at roomtemperature overnight. The polymer was precipitated with acetone,filtered, and dried.

Polyphosphates

In one embodiment, polyphosphates were used to form complex coacervateswith protamine or polyguanidine. Negatively charged phosphate andphosphonate groups form strong electrostatic bonds with guanidiumgroups. Several polyphosphates are commercially available and are usedas additives to food and consumer health care products. Sodiumhexametaphosphate (CAS#68915-31-1) was used to form the salmine complexcoacervates. Other suitable polyphosphates include sodium triphosphate(CAS#7758-29-4) and sodium inositol hexaphosphate (CAS#14306-25-3),which is also known as phytic acid. These polyphosphates arebiodegradable and non-toxic. Inositol hexaphosphate occurs naturally inplants and is sold and consumed as a neutriceutical.

Preparation of Coacervates

The sodium salt of poly(acrylamide-co-acrylamidohexanoic acid),comprising 45.8 mol % acrylamidohexanoic acid sidechains, was dissolvedat 50 mg/ml in separate solutions of 150, 300, 500, 750, and 1000 mMNaCl. Salmine sulfate (MP Biomedicals) was dissolved at 50 mg/ml inseparate solutions of 150, 300, 500, 750, and 1000 mM NaCl. Complexcoacervates were formed by adding an appropriate volume of the salminesolution at a given NaCl concentration drop wise to an appropriatevolume of the poly(acrylamide-co-acrylamidohexanoic acid) such that thefinal charge ratio was 1:1 carboxylate to arginine. The mixed solutionturned immediately cloudy and within a few minutes the complexcoacervate began to settle out on the bottom of the tube. The complexcoacervate phase was allowed to equilibrate for 24 hr, after which thepolymer-depleted upper aqueous phase is removed. The dense lower phaseis used as the in situ solidifying complex coacervate. 150 micro litersof the dense complex coacervate phase was pipetted onto the deck of therheometer with a positive displacement pipette.

The effect of ionic strength on the material properties of theassociated PEs is further illustrated in FIG. 2. The viscosity of thematerials changed by an order of magnitude in going from the in situsolidifying complex coacervate at high ionic strength to a solid gelnear physiological ionic strength.

Example 2

Using the procedure of Example 1, aqueous solutions of salmine andhexametaphosphate were mixed in various concentrations of NaCl at roomtemperature, 22° C. Between 1100 and 1200 mM NaCl a critical ionicstrength (I) exists at which the complex coacervate becomes a solidnon-flowing gel. The viscosity of the coacervate decreases withincreasing I above I_(crit). The stiffness of the gels increases belowI_(crit). The forms are interconvertible by changing the ionic strength.The results are depicted in FIG. 1.

Evaluation of In Situ Solidifying Complex Coacervates as Embolic Agents

The use of the in situ solidifying complex coacervates (salmine andhexametaphosphate) as embolic agent in an in vitro model is demonstratedin FIGS. 3 and 4. A model of a bifurcated vascular system was createdwith silicone tubing and a peristaltic pump. The system includes apressure gauge, valves for flow control, and an inlet for small diametercatheters (FIG. 3). While circulating physiological saline, a narrowgauge catheter (blue) was inserted into one side of the bifurcatedchannel (FIG. 4A). A fluid high ionic strength (1,200 mM NaCl) in situsolidifying complex coacervate injected into the physiological salineflow immediately solidified (FIG. 4B). Flow through the channel wasdiverted to the other channel, which is evident from the stationarybubble below the gelled plug (FIG. 4C, white arrow). To determine thepressure the embolic plug could withstand, the open channel was clampedto build pressure. The plug withstood a closed system pressure of 110 mmof Hg before failing in the example shown. This is within normalphysiological blood pressure for a healthy human.

Example 3. In Vivo Evaluation of In Situ Setting Adhesive Coacervates:Rabbit Kidney Embolization

A New Zealand white female rabbit weighing 4.5 kg was kept in anenvironmentally controlled animal research facility. Food was offeredonce a day and water was provided ad libitum. This investigation wascarried out under an IACUC approved protocol and following theUniversity of Utah animal research guidelines.

All surgical procedures were performed under sterile conditions. Therabbit was first anesthetized with Isoflurane in an induction chamber,then intubated with an endotracheal tube (3.5 mm, Hudson/Sheridan). Onceintubated, the rabbit was connected to an anesthetic machine (DragerNarkomed 2B) equipped for non-invasive monitoring, including ananesthetic gas analyzer, respiratory monitor (Ohmeda 5250 RGM),oximeter, thermometer, and Isoflurane vaporizer. An intravenous infusionof 0.9% saline solution (Baxter) was administered during the procedure.

Preparation of In Situ Solidifying Coacervate

Complex coacervates were prepared using protamine sulfate (MPBiomedicals, Inc.) and sodium phytate (Sigma-Aldrich, Inc.). Protaminesulfate (PRT) and sodium phytate (IP6) were dissolved in 1200 mM NaCl at62.5 mg/mL and 115.1 mg/mL, respectively, and adjusted to pH 7.2. Thesolutions were filter sterilized into sterile 50 mL conical tubesthrough a 0.22 m syringe filter (Millex-GS, Millipore). The solutions, 8mL of IP6 and 32 mL PRT, were mixed at a 1:1 positive to negative chargeratio at 60° C., above the coacervation phase separation temperature.Tantalum metal powder (1,114.3 mg, 1-5 micron particle size, AtlanticEquipment Engineers) was also added so that the condensed coacervatephase was 30 wt % tantalum. The solution was mixed continuously as itcooled to room temperature. The dense coacervated settled to the bottomon the tube. After 24 hr, the supernatant and removed and the densecoacervate phase was aseptically loaded into 1 mL syringes.

Catheterization Procedure

The right femoral artery was chosen as the site of arterialcatheterization. The inner side of the leg was shaved, and the incisionsite and surrounding skin was cleaned with 70% isopropyl alcohol. Thedisinfected area was covered with sterile drapes, exposing only the areaoverlying the right femoral artery. The artery was exposed with a 3-5 cmlongitudinal incision. The location of the incision was determined bypalpating the artery. The artery was isolated from the femoral nerve andvein by blunt dissection. Two 4.0 silk sutures were positioned under theartery and used to gently elevate the artery for access. TopicalLidocain (2%, Hospira) was administered to decrease the vasospasm of thefemoral artery during handling.

The femoral artery was accessed using a 4F access kit (Access PointTechnology, Inc). The micro-catheter (2.8 F, 135 cm/Biomerics) wasmaneuvered from the femoral artery into the renal artery underfluoroscopy (C-arm 9800 series OEC MEdical/GE medical). Omnipaque(Iohexol 240 mg/ml) was used as the X-ray contrast agent to visualizeorgans and blood vessels. Once the microcatether was positioned in therenal artery, Omnipaque diluted 1:1 with normal saline was injected tovisualize the blood vessels. The catheter was flushed with saline, then0.2 mL of hypersaline (1.2M) was injected into the catether.

The in situ solidifying adhesive coacervate was loaded into a 1 mLsyringe (Medallion, Merit Medical). The coacervate contained 30 wt %tantalum metal (1-5 micron particle size) as a contrast agent. Thesyringe was attached to the catheter and the sample was injected intothe renal artery. No changes in breathing or heart rate occurred duringor after the embolization. Injection of the adhesive was visualizedusing a C-arm 9800 series fluoroscope (OEC Medical/GE Medical Inc.).Complete occlusion of the left kidney was observed as a result ofinjecting the adhesive (FIGS. 7A and 7B). It was apparent the coacervateevenly penetrated into the fine branching blood vessels of the entirekidney cortex.

The animal was euthanized 90 min after embolization with Euthanasiasolution (Vet One). No changes were observed by fluoroscopy in theposition or opaqueness of the in situ solidifying coacervate during the90 minutes post injection. Post mortem, the animal was scanned on anAxiom Artist dBA biplane angiography system (Siemens Inc.) to obtain a3D image of the embolized kidney (FIGS. 7C and 7D). Complete and uniformembolization was apparent in the 3D images.

Histology

During necropsy, the embolized kidney was isolated and fixed in 10%buffered formalin. After 2 days, the renal capsule was removed and thetissue was fixed for another 4 days. The tissue was embedded inparaffin, sectioned and stained with Hematoxylin & Eosin (FIGS. 8A-8D).From histology, it was observed that arteries and small arteries werefully occluded. Occlusion occurred uniformly throughout the kidney,penetrating into the capillaries of glomeruli. Importantly, no embolicagent was visible in veins or venules. The adhesive coacervate appearedto adhere to the wall of the blood vessels. The adhesive coacervate didnot mix with blood, and there was no evidence of lysis of red bloodcells in direct contact with the adhesive. There was no visible effecton cells or tissues immediate adjacent to the emboli.

Example 4. Flow Behavior Studies Sample Preparation

Complex coacervates were prepared using protamine sulfate (MPBiomedicals, Inc.) and sodium phytate (Sigma-Aldrich, Inc.). Protaminesulfate (PRT) and sodium phytate (IP6) were dissolved in 1,200 mM NaClat concentrations of 62.5 mg/mL and 115.1 mg/mL, respectively, andadjusted to pH 7.2. The solutions were mixed at a ratio of 1 part IP6 to4 parts PRT to give a 1:1 positive to negative charge ratio. Thesolutions were mixed at 60° C., above the coacervation phase separationtemperature. An amount of tantalum metal powder (1-5 micron particlesize, Atlantic Equipment Engineers) was added so that the condensedcoacervate phase contained 30 wt % tantalum. The solution was mixedcontinuously as it cooled to room temperature. The dense coacervatephase settled to the bottom on the tube. After 24 hr, the supernatantphase was removed from the coacervate phase.

Oscillatory Rheology

The flow behavior of PRT/IP6 coacervates was characterized on atemperature controlled rheometer (AR 2000ex Rheometer, TA Instruments).Viscosity was measured as a function of applied shear rate using a 20mm, 40 cone geometry. A solvent trap was used to prevent the sample fromdrying out during the experiment. Shear rate was stepped from 0.01 s⁻¹to 1000 s⁻¹ at 10 points per decade. The tantalum containing coacervateswere 5-6 times more viscous at low shear rates than the non-tantalumcontaining coacervates. The tantalum coacervate shear-thinned to ˜1.2 Pas as the shear rate increased, approaching the viscosity of thenon-tantalum coacervates at high shear rates (FIG. 9). At the end of theforward sweep, the shear rate was stepped back down from 1000 s⁻¹ to0.01 s⁻¹. The viscosity of the tantalum coacervate recovered at lowshear rates. Reversible shear thinning is a critical feature of thecontrast containing coacervates; it allows the viscous composition to beinjected through a long narrow catheter with low force, and as the shearrate decreases to zero at the catheter exit, the viscosity of thecomposition increases to prevent it from flowing away from theapplication site. This allows precise control while injecting thecomposition.

Example 5. In Situ Solidifying Adhesive Phase Diagram

Aqueous mixtures of oppositely charged polyelectrolytes (PEs) can existin several material states, or forms. The form depends on solutionconditions like pH, ionic strength, and temperature. A phase diagram ofmixtures of protamine sulfate (PRT) and sodium phytate (IP6) withpositive to negative charge ratios ranging from 6:1 to 1:6, and solutionionic strengths ranging from 0.15 to 1.5 M NaCl, was created at 21° C.and 37° C. (FIG. 10). Solutions (1 ml) were made in 1.5 mL Eppendorftubes at 60° C. by combining appropriate volumes of 100 mg/mL stocksolutions of PRT and IP6 at pH 7.2, 5 M NaCl, H₂O. PRT was addeddropwise to the other components while vortexing. The solutions wereincubated at 37° C. As the solutions cooled to 37° C. the PEs condensedand separated into dense fluid (coacervate) or solid (gel) phases. Afterequilibrating at 37° C. for 24 hr, the form of the condensed PE phasewere visibly scored as coacervate or gel by whether it flowed whentilted (coacervate) or not (gel). The solutions were then cooled to 21°C. and scored again after 24 hr.

The form of the electrostatically associated oppositely charged PEs isdependent on the NaCl concentration. Higher salt concentrations shieldelectrostatic interactions and decrease the strength of the PEassociation, resulting in a fluid coacervate form. At low salt, theinteractions are stronger, resulting in strongly associated solid gelforms. At very high salt concentrations the PE charges are fullyshielded and the PEs do not associate. In this case the PEs are fullysolvated and suspended in the aqueous solution; no phase separationoccurs. Temperature also affects the strength of the PE association. Athigher temperatures the electrostatic interactions are weaker and hencethe PEs condense into a liquid coacervate form at lower NaClconcentrations. The strength of the association between PEs is highestwhen the maximum number of charge interactions occurs, which is when thecharge ratio is 1:1.

The phase diagrams illustrate the principle of the invention. By mixingPEs in a region of the phase diagram in which fluid complex coacervatescondense, the adhesive can be prepared in an injectable fluid form. Ifthe fluid form is injected into an environment corresponding to a gelregion of the phase diagram, the fluid form will harden into a solid gelas the adhesive equilibrates to the new solution conditions. From thephase diagrams in FIG. 10, it can be observed that a fluid coacervateform of the adhesive can be prepared at NaCl concentrations ranging from600 mM to 1,500 mM. When the fluid coacervate is injected into anenvironment with less than 300 mM NaCl at 37° C., i.e., humanphysiological conditions, the fluid form will spontaneously transitionto a solid gel form in situ.

Throughout this application, various publications are referenced. Thedisclosures of these publications in their entireties are herebyincorporated by reference into this application in order to more fullydescribe the compounds, compositions and methods described herein.

Various modifications and variations can be made to the compounds,compositions and methods described herein. Other aspects of thecompounds, compositions and methods described herein will be apparentfrom consideration of the specification and practice of the compounds,compositions and methods disclosed herein. It is intended that thespecification and examples be considered as exemplary.

What is claimed:
 1. A method for reducing or inhibiting blood flow in ablood vessel of a subject comprising introducing into the vessel ahomogeneous solution comprising water, at least one polycation, at leastone polyanion, and monovalent ions in water, wherein the concentrationof the monovalent ions in the homogeneous solution is greater than theconcentration of the monovalent ions in the blood vessel of the subject,whereupon introduction of the homogeneous solution into the vessel thehomogeneous solution is converted to a solid in situ within the vessel.2. The method of claim 1, wherein the method reduces or inhibits bloodflow to a tumor, an aneurysm, a varicose vein, an arteriovenousmalformation, or a bleeding wound.
 3. The method of claim 1, wherein themethod reinforces the inner wall of a blood vessel in the subject. 4.The method of claim 1, wherein the concentration of the monovalent ionsin the homogeneous solution is 1.5 to 10 times greater than theconcentration of the monovalent ions in the blood vessel of the subject.5. The method of claim 1, wherein the monovalent ions in the homogeneoussolution are sodium ions and chloride ions.
 6. The method of claim 1,wherein the total positive/negative charge ratio of the polycation tothe polyanion is from 4 to 0.25 and the concentration of the eachmonovalent ion in the homogeneous solution is from 0.5 M to 2.0 M. 7.The method of claim 1, wherein the homogeneous solution furthercomprises a salt that produces monovalent ions, wherein the salt isNaCl.
 8. The method of claim 1, wherein the homogeneous solution has apH of 6 to
 9. 9. The method of claim 1, wherein the polycation comprisesa polyamino compound, wherein the polyamino compound comprises a naturalpolymer or a synthetic polymer having two or more guanidinyl sidechains.10. The method of claim 1, wherein the polycation comprises apolyacrylate comprising two or more pendant amino groups.
 11. The methodof claim 10, wherein the amino group comprises an alkylamino group, aheteroaryl group, a guanidinyl group, an imidazole, or an aromatic groupsubstituted with one or more amino groups, a primary amino group, asecondary amino group, tertiary amino group, or a quaternary amine. 12.The method of claim 1, wherein the polycation is syntheticpolyguanidinyl polymer comprising an acrylate, methacrylate, acrylamide,or methacrylamide backbone and two or more guanidinyl groups pendant tothe backbone.
 13. The method of claim 1, wherein the polycation is asynthetic polyguanidinyl polymer comprising the polymerization productbetween a monomer selected from the group consisting of an acrylate, amethacrylate, an acrylamide, a methacrylamide, or any combinationthereof and a compound of formula I

wherein R¹ is hydrogen or an alkyl group, X is oxygen or NR⁵, where R⁵is hydrogen or an alkyl group, and m is from 1 to 10, or thepharmaceutically-acceptable salt thereof.
 14. The method of claim 13,wherein the polycation comprises polymerization product between thecompound of formula I and methacrylamide.
 15. The method of claim 13,wherein R¹ is methyl, X is NH, m is
 3. 16. The method of claim 1,wherein the polyanion comprises a polyphosphate.
 17. The method of claim1, wherein the polyanion is an inorganic polyphosphate or aphosphorylated sugar.
 18. The method of claim 1, wherein the polyanioncomprises a hexametaphosphate salt.
 19. The method of claim 1, whereinthe polyanion is inositol hexaphosphate.
 20. The method of claim 1,wherein the polyanion comprises a polyacrylate comprising two or morependant phosphate groups.
 21. The method of claim 1, wherein thepolyanion is the copolymerization product between a phosphate orphosphonate acrylate and/or phosphate or phosphonate methacrylate withone or more additional polymerizable monomers.
 22. The method of claim1, wherein the homogeneous solution further comprises a contrast agentor a visualization agent.
 23. The method of claim 22, wherein thecontrast agent comprises tantalum particles, gold particles, or aniodine complex.
 24. The method of claim 1, wherein the homogeneoussolution further comprises a reinforcing component.
 25. The method ofclaim 24, wherein the reinforcing component comprises natural orsynthetic fibers, water-insoluble filler particles, a nanoparticle, or amicroparticle.
 26. The method of claim 1, wherein the homogeneoussolution further comprises one or more bioactive agents.
 27. The methodof claim 26, wherein the bioactive agent comprises an antibiotic, a painreliever, an immune modulator, a growth factor, an enzyme inhibitor, ahormone, a mediator, a messenger molecule, a cell signaling molecule, areceptor agonist, an oncolytic, a chemotherapy agent, a receptorantagonist, a nucleic acid, or any combination thereof.
 28. The methodof claim 1, wherein the polycation is a synthetic polyguanidino polymercomprising the polymerization product between a monomer selected fromthe group consisting of an acrylate, a methacrylate, an acrylamide, amethacrylamide, or any combination thereof and a compound of formula I

wherein R¹ is hydrogen or an alkyl group, X is oxygen or NR⁵, where R⁵is hydrogen or an alkyl group, and m is 3, or thepharmaceutically-acceptable salt thereof, the polyanion comprises sodiumhexametaphosphate, the total positive/negative charge ratio of thepolycation solution to the polyanion is from 0.95 to 1.10 and thehomogeneous solution further comprises NaCl, wherein the concentrationof sodium ions in the homogeneous solution is from 0.5 M to 2.0 M andthe concentration of the chloride ions in the homogeneous solution isfrom 0.5 M to 2.0 M.